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125 | 1 | 126 | null | 1 | 770 | I want learn about NoSQL and when is better to use SQL or NoSQL. I know that this question depends on the case, but I'm asking for a good documentation on NoSQL, and some explanation of when is better to use SQL or NoSQL (use cases, etc). Also, your opinions on NoSQL databases, and any recommendations for learning abou... | How to learn noSQL databases and how to know when SQL or noSQL is better | CC BY-SA 3.0 | null | 2014-05-17T21:52:34.563 | 2021-03-15T21:14:08.800 | 2014-05-18T16:10:50.820 | 84 | null | [
"nosql"
] |
126 | 2 | null | 125 | 2 | null | Please have a look at my answer here:
[Motivations for using relational database / ORM or document database / ODM](https://stackoverflow.com/questions/13528216/motivations-for-using-relational-database-orm-or-document-database-odm/13599767#13599767)
Short version:
- Use NoSQL when data size and number of transactions... | null | CC BY-SA 3.0 | null | 2014-05-17T23:53:42.700 | 2016-04-11T22:08:14.620 | 2017-05-23T12:38:53.587 | -1 | 26 | null |
128 | 1 | 296 | null | 62 | 31257 | [Latent Dirichlet Allocation (LDA)](http://en.wikipedia.org/wiki/Latent_Dirichlet_allocation) and [Hierarchical Dirichlet Process (HDP)](http://en.wikipedia.org/wiki/Hierarchical_Dirichlet_process) are both topic modeling processes. The major difference is LDA requires the specification of the number of topics, and HDP... | Latent Dirichlet Allocation vs Hierarchical Dirichlet Process | CC BY-SA 3.0 | null | 2014-05-18T06:10:52.543 | 2021-02-04T09:10:56.807 | 2014-05-20T13:45:59.373 | 84 | 122 | [
"nlp",
"topic-model",
"lda"
] |
129 | 1 | 166 | null | 10 | 1581 | [This question](https://stackoverflow.com/questions/879432/what-is-the-difference-between-a-generative-and-discriminative-algorithm) asks about generative vs. discriminative algorithm, but can someone give an example of the difference between these forms when applied to Natural Language Processing? How are generative a... | What is generative and discriminative model? How are they used in Natural Language Processing? | CC BY-SA 3.0 | null | 2014-05-18T06:17:37.587 | 2014-05-19T11:13:48.067 | 2017-05-23T12:38:53.587 | -1 | 122 | [
"nlp",
"language-model"
] |
130 | 1 | 132 | null | 70 | 39376 | From wikipedia:
>
dimensionality reduction or dimension reduction is the process of
reducing the number of random variables under consideration, and
can be divided into feature selection and feature extraction.
What is the difference between feature selection and feature extraction?
What is an example of dimensional... | What is dimensionality reduction? What is the difference between feature selection and extraction? | CC BY-SA 4.0 | null | 2014-05-18T06:26:15.673 | 2021-02-07T20:32:33.683 | 2021-02-07T20:32:33.683 | 29169 | 122 | [
"feature-selection",
"feature-extraction",
"dimensionality-reduction"
] |
131 | 2 | null | 115 | 9 | null | Look it up on:
- Google Scholar link
- Citeseer link
If you get a single exact title match then you have probably found the right article, and can fill in the rest of the info from there. Both give you download links and bibtex-style output. What you would likely want to do though to get perfect metadata is downl... | null | CC BY-SA 3.0 | null | 2014-05-18T06:54:08.560 | 2014-05-18T06:54:08.560 | null | null | 26 | null |
132 | 2 | null | 130 | 57 | null | Simply put:
- feature selection: you select a subset of the original feature set; while
- feature extraction: you build a new set of features from the original feature set.
Examples of feature extraction: extraction of contours in images, extraction of digrams from a text, extraction of phonemes from recording of... | null | CC BY-SA 3.0 | null | 2014-05-18T07:53:58.203 | 2014-05-18T07:53:58.203 | null | null | 172 | null |
133 | 2 | null | 103 | 11 | null |
- I think a number of clustering algorithms that normally use a metric, do not actually rely on the metric properties (other than commutativity, but I think you'd have that here). For example, DBSCAN uses epsilon-neighborhoods around a point; there is nothing in there that specifically says the triangle inequality ma... | null | CC BY-SA 3.0 | null | 2014-05-18T09:09:47.780 | 2014-05-18T09:17:15.557 | 2014-05-18T09:17:15.557 | 26 | 26 | null |
134 | 1 | 246 | null | 11 | 703 | In our company, we have a MongoDB database containing a lot of unstructured data, on which we need to run map-reduce algorithms to generate reports and other analyses. We have two approaches to select from for implementing the required analyses:
- One approach is to extract the data from MongoDB to a Hadoop cluster an... | Can map-reduce algorithms written for MongoDB be ported to Hadoop later? | CC BY-SA 3.0 | null | 2014-05-18T12:03:21.650 | 2014-06-10T02:42:02.050 | null | null | 227 | [
"scalability",
"apache-hadoop",
"map-reduce",
"mongodb"
] |
135 | 2 | null | 41 | 9 | null | Considering another criteria, I think that in some cases using Python may be much superior to R for Big Data. I know the wide-spread use of R in data science educational materials and the good data analysis libraries available for it, but sometimes it just depend on the team.
In my experience, for people already famili... | null | CC BY-SA 3.0 | null | 2014-05-18T12:30:06.853 | 2014-05-19T08:13:05.037 | 2014-05-19T08:13:05.037 | 227 | 227 | null |
136 | 5 | null | null | 0 | null | MapReduce is a framework for processing parallelizable problems across huge datasets using a large number of computers (nodes), collectively referred to as a cluster (if all nodes are on the same local network and use similar hardware) or a grid (if the nodes are shared across geographically and administratively distri... | null | CC BY-SA 4.0 | null | 2014-05-18T12:55:39.657 | 2021-02-10T14:59:02.167 | 2021-02-10T14:59:02.167 | 111611 | 227 | null |
137 | 4 | null | null | 0 | null | MapReduce is a programming model for processing large data sets with a parallel, distributed algorithm on a cluster. | null | CC BY-SA 3.0 | null | 2014-05-18T12:55:39.657 | 2014-05-20T13:53:39.727 | 2014-05-20T13:53:39.727 | 227 | 227 | null |
138 | 1 | 251 | null | 10 | 223 | Any small database processing can be easily tackled by Python/Perl/... scripts, that uses libraries and/or even utilities from the language itself. However, when it comes to performance, people tend to reach out for C/C++/low-level languages. The possibility of tailoring the code to the needs seems to be what makes the... | Why is it hard to grant efficiency while using libraries? | CC BY-SA 3.0 | null | 2014-05-18T14:02:51.350 | 2014-06-10T05:57:13.897 | 2014-05-29T15:01:17.840 | 84 | 84 | [
"bigdata",
"efficiency",
"performance"
] |
139 | 2 | null | 76 | 3 | null | I'd suggest [Apache Kafka](http://kafka.apache.org) as message store and any stream processing solution of your choice like [Apache Camel](https://camel.apache.org) or [Twitter Storm](https://github.com/apache/incubator-storm)
| null | CC BY-SA 3.0 | null | 2014-05-18T14:04:37.870 | 2014-05-18T14:04:37.870 | null | null | 118 | null |
140 | 2 | null | 107 | 4 | null | I've read very good [article](http://www.michael-noll.com/blog/2013/01/18/implementing-real-time-trending-topics-in-storm/) recently that suggests using [Twitter storm](https://github.com/nathanmarz/storm) for a task that looks pretty similar to yours.
| null | CC BY-SA 3.0 | null | 2014-05-18T14:30:10.553 | 2014-05-18T14:30:10.553 | null | null | 118 | null |
141 | 5 | null | null | 0 | null | null | CC BY-SA 3.0 | null | 2014-05-18T14:36:16.350 | 2014-05-18T14:36:16.350 | 2014-05-18T14:36:16.350 | -1 | -1 | null | |
142 | 4 | null | null | 0 | null | Efficiency, in algorithmic processing, is usually associated to resource usage. The metrics to evaluate the efficiency of a process are commonly account for execution time, memory/disk or storage requirements, network usage and power consumption. | null | CC BY-SA 3.0 | null | 2014-05-18T14:36:16.350 | 2014-05-20T13:51:49.240 | 2014-05-20T13:51:49.240 | 84 | 84 | null |
143 | 1 | 165 | null | 10 | 1015 | As we all know, there are some data indexing techniques, using by well-known indexing apps, like Lucene (for java) or Lucene.NET (for .NET), MurMurHash, B+Tree etc. For a No-Sql / Object Oriented Database (which I try to write/play a little around with C#), which technique you suggest?
I read about MurMurhash-2 and spe... | What is the most efficient data indexing technique | CC BY-SA 3.0 | null | 2014-05-18T14:37:20.477 | 2014-05-19T12:05:13.513 | 2014-05-19T12:05:13.513 | 229 | 229 | [
"nosql",
"efficiency",
"indexing",
"data-indexing-techniques",
".net"
] |
144 | 5 | null | null | 0 | null | [Cluster analysis](http://en.wikipedia.org/wiki/Cluster_analysis) is the task of grouping objects into subsets (called clusters) so that observations in the same cluster are similar in some sense, while observations in different clusters are dissimilar.
In [machine-learning](/questions/tagged/machine-learning) and [dat... | null | CC BY-SA 3.0 | null | 2014-05-18T14:58:34.853 | 2018-01-01T18:56:53.570 | 2018-01-01T18:56:53.570 | 29575 | 29575 | null |
145 | 4 | null | null | 0 | null | Cluster analysis or clustering is the task of grouping a set of objects in such a way that objects in the same group (called a cluster) are more similar (in some sense or another) to each other than to those in other groups (clusters). It is a main task of exploratory data mining, and a common technique for statistical... | null | CC BY-SA 3.0 | null | 2014-05-18T14:58:34.853 | 2014-05-20T13:53:26.907 | 2014-05-20T13:53:26.907 | 118 | 118 | null |
146 | 5 | null | null | 0 | null | Natural language processing (NLP) is a subfield of artificial intelligence that involves transforming or extracting useful information from natural language data. Methods include machine-learning and rule-based approaches. It is often regarded as the engineering arm of Computational Linguistics.
NLP tasks
- Text pre-p... | null | CC BY-SA 3.0 | null | 2014-05-18T15:01:24.080 | 2018-04-10T01:03:28.253 | 2018-04-10T01:03:28.253 | 21163 | 29575 | null |
147 | 4 | null | null | 0 | null | Natural language processing (NLP) is a field of computer science, artificial intelligence, and linguistics concerned with the interactions between computers and human (natural) languages. As such, NLP is related to the area of human–computer interaction. Many challenges in NLP involve natural language understanding, th... | null | CC BY-SA 3.0 | null | 2014-05-18T15:01:24.080 | 2014-05-20T13:52:59.427 | 2014-05-20T13:52:59.427 | 118 | 118 | null |
148 | 5 | null | null | 0 | null | In Computer science and Technologies The Data is the most important part.
Since to work with data in an efficient manner to store the data in mediums and reuse, we use some techniques which named in general indexing.
This tag interests with these techniques, efficiency, and anything about using stored data with indexin... | null | CC BY-SA 3.0 | null | 2014-05-18T15:08:08.913 | 2014-05-20T13:53:31.717 | 2014-05-20T13:53:31.717 | 229 | 229 | null |
149 | 4 | null | null | 0 | null | In Computer science and Technologies The Data is the most important part.
Since to work with data in an efficient manner to store the data in mediums and reuse, we use some techniques which named in general indexing.
This tag interests with these techniques, efficiency, and anything about using stored data with ind... | null | CC BY-SA 3.0 | null | 2014-05-18T15:08:08.913 | 2014-05-20T13:52:19.333 | 2014-05-20T13:52:19.333 | 229 | 229 | null |
151 | 5 | null | null | 0 | null | Indexing is the almost most important part of data to get an efficient, properly storing and retrieval data from mediums
In different Programming Languages, there are different indexing algorithms and structures can be found.
As an Example, in Java Language the Apache Foundation's Lucene is very popular.
In years there... | null | CC BY-SA 3.0 | null | 2014-05-18T15:34:16.437 | 2014-05-20T13:48:12.163 | 2014-05-20T13:48:12.163 | 229 | 229 | null |
152 | 4 | null | null | 0 | null | Indexing is the almost most important part of data to get an efficient, properly storing and retrieval data from mediums | null | CC BY-SA 3.0 | null | 2014-05-18T15:34:16.437 | 2014-05-20T13:53:17.567 | 2014-05-20T13:53:17.567 | 229 | 229 | null |
153 | 2 | null | 81 | 3 | null | The answers presented so far are very nice, but I was also expecting an emphasis on a particular difference between parallel and distributed processing: the code executed. Considering parallel processes, the code executed is the same, regardless of the level of parallelism (instruction, data, task). You write a single ... | null | CC BY-SA 3.0 | null | 2014-05-18T17:38:01.383 | 2014-05-18T17:38:01.383 | null | null | 84 | null |
154 | 2 | null | 125 | 3 | null | Check [Martin Fowler's Personal website](http://www.martinfowler.com). He writes good and specially answers one of your questions in his book: "NoSQL Distilled"
| null | CC BY-SA 4.0 | null | 2014-05-18T17:53:37.750 | 2021-03-15T21:14:08.800 | 2021-03-15T21:14:08.800 | 29169 | 229 | null |
155 | 1 | 158 | null | 201 | 32456 | One of the common problems in data science is gathering data from various sources in a somehow cleaned (semi-structured) format and combining metrics from various sources for making a higher level analysis. Looking at the other people's effort, especially other questions on this site, it appears that many people in thi... | Publicly Available Datasets | CC BY-SA 3.0 | null | 2014-05-18T18:45:38.957 | 2022-07-01T05:57:50.363 | 2016-12-05T22:33:53.380 | 26596 | 227 | [
"open-source",
"dataset"
] |
156 | 2 | null | 155 | 38 | null | [Freebase](https://www.freebase.com) is a free community driven database that spans many interesting topics and contains about 2,5 billion facts in machine readable format. It is also have good API to perform data queries.
[Here](http://www.datapure.co/open-data-sets) is another compiled list of open data sets
| null | CC BY-SA 4.0 | null | 2014-05-18T19:19:44.240 | 2021-07-08T20:42:25.690 | 2021-07-08T20:42:25.690 | 120060 | 118 | null |
157 | 2 | null | 41 | 12 | null | R is great for "big data"! However, you need a workflow since R is limited (with some simplification) by the amount of RAM in the operating system. The approach I take is to interact with a relational database (see the `RSQLite` package for creating and interacting with a SQLite databse), run SQL-style queries to under... | null | CC BY-SA 3.0 | null | 2014-05-18T19:22:05.160 | 2014-05-18T19:22:05.160 | null | null | 36 | null |
158 | 2 | null | 155 | 111 | null | There is, in fact, a very reasonable list of publicly-available datasets, supported by different enterprises/sources.
Some of them are below:
- Public Datasets on Amazon WebServices;
- Frequent Itemset Mining Implementation Repository;
- UCI Machine Learning Repository;
- KDnuggets -- a big list of lots of public ... | null | CC BY-SA 3.0 | null | 2014-05-18T19:29:53.530 | 2016-11-29T04:04:46.463 | 2016-11-29T04:04:46.463 | 26596 | 84 | null |
159 | 1 | 160 | null | 6 | 558 | I see a lot of courses in Data Science emerging in the last 2 years. Even big universities like Stanford and Columbia offers MS specifically in Data Science. But as long as I see, it looks like data science is just a mix of computer science and statistics techniques.
So I always think about this. If it is just a trend ... | Is Data Science just a trend or is a long term concept? | CC BY-SA 3.0 | null | 2014-05-18T19:46:44.653 | 2014-05-18T21:05:28.990 | null | null | 199 | [
"bigdata",
"machine-learning",
"databases",
"statistics",
"education"
] |
160 | 2 | null | 159 | 12 | null | The one thing that you can say for sure is: Nobody can say this for sure. And it might indeed be opinion-based to some extent. The introduction of terms like "Big Data" that some people consider as "hypes" or "buzzwords" don't make it easier to flesh out an appropriate answer here. But I'll try.
In general, interdisci... | null | CC BY-SA 3.0 | null | 2014-05-18T21:05:28.990 | 2014-05-18T21:05:28.990 | null | null | 156 | null |
161 | 2 | null | 138 | 7 | null | I don't think that everyone reaches for C/C++ when performance is an issue.
The advantage to writing low-level code is using fewer CPU cycles, or sometimes, less memory. But I'd note that higher-level languages can call down to lower-level languages, and do, to get some of this value. Python and JVM languages can do th... | null | CC BY-SA 3.0 | null | 2014-05-18T21:25:29.040 | 2014-05-18T21:25:29.040 | null | null | 21 | null |
162 | 2 | null | 155 | 44 | null | There are many openly available data sets, one many people often overlook is [data.gov](http://www.data.gov/). As mentioned previously Freebase is great, so are all the examples posted by @Rubens
| null | CC BY-SA 3.0 | null | 2014-05-18T22:16:19.300 | 2014-05-18T22:16:19.300 | null | null | 59 | null |
163 | 2 | null | 138 | 4 | null | As all we know, in Digital world there are many ways to do the same work / get expected results..
And responsibilities / risks which comes from the code are on developers' shoulders..
This is small but i guess a very useful example from .NET world..
So Many .NET developers use the built-in BinaryReader - BinaryWriter o... | null | CC BY-SA 3.0 | null | 2014-05-18T23:21:07.220 | 2014-05-18T23:29:39.227 | 2014-05-18T23:29:39.227 | 229 | 229 | null |
164 | 2 | null | 14 | 11 | null | What @Clayton posted seems about right to me, for those terms, and for "data mining" being one tool of the data scientist. However, I haven't really used the term "data collection," and it doesn't strike me as synonymous with "data mining."
My own answer to your question: no, the terms aren't the same. Definitions may ... | null | CC BY-SA 3.0 | null | 2014-05-19T00:09:17.900 | 2014-05-19T00:09:17.900 | null | null | 208 | null |
165 | 2 | null | 143 | 10 | null | I think you messed up some things in your question. Lucene (I know nothing about Lucene,NET, but I suppose is the same) is a library used to analyze, split in tokens, and store documents in order to be able to query and retrieve them later. Lucene has a pretty old but effective model, it uses inverted trees to find and... | null | CC BY-SA 3.0 | null | 2014-05-19T08:46:47.683 | 2014-05-19T08:46:47.683 | null | null | 108 | null |
166 | 2 | null | 129 | 8 | null | Let's say you are predicting the topic of a document given its words.
A generative model describes how likely each topic is, and how likely words are given the topic. This is how it says documents are actually "generated" by the world -- a topic arises according to some distribution, words arise because of the topic, y... | null | CC BY-SA 3.0 | null | 2014-05-19T11:13:48.067 | 2014-05-19T11:13:48.067 | null | null | 21 | null |
167 | 5 | null | null | 0 | null | .NET is a very popular Object Oriented Programming Language Family.This Family includes members such as C# (pronounced CSharp), VB.NET, F# (pronounced Fsharp), J# (pronounced JSharp) and much more. The .NET Family offers programming with small effort with well-known high speed of compiled languages such as C and C++
Th... | null | CC BY-SA 3.0 | null | 2014-05-19T12:17:45.960 | 2014-05-20T13:52:50.373 | 2014-05-20T13:52:50.373 | 229 | 229 | null |
168 | 4 | null | null | 0 | null | .NET is a very popular Object Oriented Programming Language Family which includes members such as C# (pronounced CSharp), VB.NET, F# (pronounced FSharp), J# (pronounced JSharp) and much more. The .NET Family offers programming with small effort with well-known high speed of compiled languages such as C and C++
This ... | null | CC BY-SA 3.0 | null | 2014-05-19T12:17:45.960 | 2014-05-20T13:50:32.440 | 2014-05-20T13:50:32.440 | 229 | 229 | null |
169 | 1 | 170 | null | 15 | 5505 | Assume a set of loosely structured data (e.g. Web tables/Linked Open Data), composed of many data sources. There is no common schema followed by the data and each source can use synonym attributes to describe the values (e.g. "nationality" vs "bornIn").
My goal is to find some "important" attributes that somehow "defi... | How to specify important attributes? | CC BY-SA 3.0 | null | 2014-05-19T15:55:24.983 | 2021-03-11T20:12:24.030 | 2015-05-18T13:30:46.940 | 113 | 113 | [
"machine-learning",
"statistics",
"feature-selection"
] |
170 | 2 | null | 169 | 16 | null | A possible solution is to calculate the [information gain](http://en.wikipedia.org/wiki/Decision_tree_learning#Information_gain) associated to each attribute:
$$I_{E}(f) = - \sum \limits_{i = 1}^m f_ilog_2f_i$$
Initially you have the whole dataset, and compute the information gain of each item. The item with the best i... | null | CC BY-SA 4.0 | null | 2014-05-19T18:08:32.327 | 2021-03-11T20:12:24.030 | 2021-03-11T20:12:24.030 | 29169 | 84 | null |
171 | 2 | null | 35 | 5 | null | Two things you might find useful:
- meta-learning to speedup the search for the right model and the optimal parameters.
Meta learning consists in applying machine learning tools to the problem of finding the right machine learning tool/parameters for the problem at hand. This for instance this paper for a practical ex... | null | CC BY-SA 3.0 | null | 2014-05-19T19:44:48.500 | 2014-05-19T19:44:48.500 | null | null | 172 | null |
172 | 1 | null | null | 27 | 19451 | I have a modeling and scoring program that makes heavy use of the `DataFrame.isin` function of pandas, searching through lists of facebook "like" records of individual users for each of a few thousand specific pages. This is the most time-consuming part of the program, more so than the modeling or scoring pieces, simpl... | Is there a straightforward way to run pandas.DataFrame.isin in parallel? | CC BY-SA 3.0 | null | 2014-05-19T23:59:58.070 | 2020-08-02T12:40:19.397 | 2014-05-20T04:47:25.207 | 84 | 250 | [
"performance",
"python",
"pandas",
"parallel"
] |
173 | 2 | null | 35 | 4 | null | Guessing it's likely you've seen this [YouTube demo](http://www.youtube.com/watch?v=1GhNXHCQGsM) and the related [Google Tech Talk](http://www.youtube.com/watch?v=lmG_FjG4Dy8), which is related to these papers:
- P-N Learning: Bootstrapping Binary Classifiers by Structural Constraints
- Tracking-Learning-Detection
... | null | CC BY-SA 3.0 | null | 2014-05-20T03:56:43.147 | 2014-05-20T03:56:43.147 | null | null | 158 | null |
174 | 2 | null | 116 | 5 | null | Another suggestion is to test the [logistic regression](http://en.wikipedia.org/wiki/Logistic_regression). As an added bonus, the weights (coefficients) of the model will give you an idea of which sites are age-distriminant.
Sklearn offers the [sklearn.linear_model.LogisticRegression](http://scikit-learn.org/stable/... | null | CC BY-SA 3.0 | null | 2014-05-20T09:24:30.697 | 2014-05-20T19:36:16.283 | 2014-05-20T19:36:16.283 | 172 | 172 | null |
175 | 1 | null | null | 3 | 62 | I have data coming from a source system that is pipe delimited. Pipe was selected over comma since it was believed no pipes appeared in field, while it was known that commas do occur. After ingesting this data into Hive however it has been discovered that rarely a field does in fact contain a pipe character.
Due to a c... | Can metadata be used to adapt parsing for an unescaped in field use of the delimiter? | CC BY-SA 3.0 | null | 2014-05-20T22:14:02.927 | 2014-05-21T07:19:32.297 | null | null | 249 | [
"metadata",
"parsing"
] |
176 | 1 | 190 | null | 12 | 4786 | I am seeking for a library/tool to visualize how social network changes when new nodes/edges are added to it.
One of the existing solutions is [SoNIA: Social Network Image Animator](http://www.stanford.edu/group/sonia/). It let's you make movies like [this one](https://www.youtube.com/watch?v=yGSNCED6mDc).
SoNIA's doc... | How to animate growth of a social network? | CC BY-SA 3.0 | null | 2014-05-21T05:29:36.787 | 2014-05-22T12:14:49.727 | 2014-05-21T05:51:58.330 | 173 | 173 | [
"social-network-analysis",
"time-series",
"javascript",
"visualization"
] |
177 | 5 | null | null | 0 | null | [MongoDB](https://www.mongodb.com) is a [widely used](https://www.mongodb.com/who-uses-mongodb), [general-purpose](https://www.mongodb.com/use-cases), [document-oriented NoSQL database](https://en.wikipedia.org/wiki/Document-oriented_database) with features including high-availability replication and auto-sharding for ... | null | CC BY-SA 4.0 | null | 2014-05-21T07:05:44.780 | 2019-04-08T13:45:37.843 | 2019-04-08T13:45:37.843 | 201 | 201 | null |
178 | 4 | null | null | 0 | null | MongoDB is a scalable, high-performance, open source, document-oriented NoSQL database. It supports a large number of languages and application development platforms. Questions about server administration can be asked on http://dba.stackexchange.com. | null | CC BY-SA 4.0 | null | 2014-05-21T07:05:44.780 | 2019-04-08T17:28:18.497 | 2019-04-08T17:28:18.497 | 201 | 201 | null |
179 | 2 | null | 176 | 6 | null | My first guess is to [visualize social network in Tableau](https://www.google.com/search?q=visualize%20social%20network%20in%20tableau).
And particularly: [building network graphs in Tableau](http://www.clearlyandsimply.com/clearly_and_simply/2012/12/build-network-graphs-in-tableau.html).
What you need is to add time d... | null | CC BY-SA 3.0 | null | 2014-05-21T07:09:20.093 | 2014-05-21T07:18:48.453 | 2014-05-21T07:18:48.453 | 97 | 97 | null |
180 | 5 | null | null | 0 | null | Neo4j is a open-source, transactional, high performance native graph database.
Neo4j stores its data as a graph: Nodes are connected through Relationships, both with arbitrary properties. Neo4j features a graph-centric declarative query language called [Cypher](http://neo4j.com/docs/stable/cypher-refcard). Its drivers ... | null | CC BY-SA 4.0 | null | 2014-05-21T07:10:45.827 | 2019-04-08T13:45:45.567 | 2019-04-08T13:45:45.567 | 201 | 201 | null |
181 | 4 | null | null | 0 | null | Neo4j is an open-source graph database (GDB) well suited to connected data. Please mention your exact version of Neo4j when asking questions. You can use it for recommendation engines, fraud detection, graph-based search, network ops/security, and many other user cases. The database is accessed via official drivers in... | null | CC BY-SA 4.0 | null | 2014-05-21T07:10:45.827 | 2019-04-08T13:45:18.490 | 2019-04-08T13:45:18.490 | 201 | 201 | null |
182 | 2 | null | 175 | 4 | null | So, a few of your rows will have too many columns by one or more as a result. That's easy to detect, but harder to infer where the error was -- which two columns are actually one? which delimiter is not a delimiter?
In some cases, you can use the metadata, because it helps you know when an interpretation of the columns... | null | CC BY-SA 3.0 | null | 2014-05-21T07:19:32.297 | 2014-05-21T07:19:32.297 | null | null | 21 | null |
183 | 2 | null | 176 | 12 | null |
### Fancy animations are cool
I was very impressed when I saw [this animation](http://youtu.be/T7Ncmq6scck) of the [discourse](http://www.discourse.org) git repository. They used [Gourse](https://code.google.com/p/gource/) which is specifically for git. But it may give ideas about how to represent the dynamics of gr... | null | CC BY-SA 3.0 | null | 2014-05-21T10:53:26.870 | 2014-05-21T15:39:57.380 | 2020-06-16T11:08:43.077 | -1 | 262 | null |
184 | 1 | 185 | null | 9 | 520 | The details of the Google Prediction API are on this [page](https://developers.google.com/prediction/), but I am not able to find any details about the prediction algorithms running behind the API.
So far I have gathered that they let you provide your preprocessing steps in PMML format.
| Google prediction API: What training/prediction methods Google Prediction API employs? | CC BY-SA 3.0 | null | 2014-05-21T11:22:34.657 | 2014-06-10T04:47:13.040 | null | null | 200 | [
"tools"
] |
185 | 2 | null | 184 | 6 | null | If you take a look over the specifications of PMML which you can find [here](http://www.dmg.org/v3-0/GeneralStructure.html) you can see on the left menu what options you have (like ModelTree, NaiveBayes, Neural Nets and so on).
| null | CC BY-SA 3.0 | null | 2014-05-21T14:14:38.797 | 2014-05-21T14:14:38.797 | null | null | 108 | null |
186 | 1 | 187 | null | 9 | 345 | I'm learning [Support Vector Machines](http://en.wikipedia.org/wiki/Support_vector_machine), and I'm unable to understand how a class label is chosen for a data point in a binary classifier. Is it chosen by consensus with respect to the classification in each dimension of the separating hyperplane?
| Using SVM as a binary classifier, is the label for a data point chosen by consensus? | CC BY-SA 3.0 | null | 2014-05-21T15:12:18.980 | 2014-05-21T15:39:54.830 | 2014-05-21T15:26:02.533 | 84 | 133 | [
"svm",
"classification",
"binary"
] |
187 | 2 | null | 186 | 9 | null | The term consensus, as far as I'm concerned, is used rather for cases when you have more a than one source of metric/measure/choice from which to make a decision. And, in order to choose a possible result, you perform some average evaluation/consensus over the values available.
This is not the case for SVM. The algorit... | null | CC BY-SA 3.0 | null | 2014-05-21T15:39:54.830 | 2014-05-21T15:39:54.830 | null | null | 84 | null |
188 | 2 | null | 134 | 5 | null | You can use map reduce algorithms in Hadoop without programming them in Java. It is called streaming and works like Linux piping. If you believe that you can port your functions to read and write to terminal, it should work nicely. [Here](http://www.michael-noll.com/tutorials/writing-an-hadoop-mapreduce-program-in-pyth... | null | CC BY-SA 3.0 | null | 2014-05-21T16:13:25.590 | 2014-05-21T16:13:25.590 | null | null | 82 | null |
189 | 1 | null | null | 4 | 983 | I'm currently using [General Algebraic Modeling System](http://en.wikipedia.org/wiki/General_Algebraic_Modeling_System) (GAMS), and more specifically CPLEX within GAMS, to solve a very large mixed integer programming problem. This allows me to parallelize the process over 4 cores (although I have more, CPLEX utilizes a... | Open source solver for large mixed integer programming task? | CC BY-SA 3.0 | null | 2014-05-21T19:41:19.857 | 2014-06-17T16:18:02.437 | 2014-06-17T16:18:02.437 | 84 | 151 | [
"r",
"open-source",
"parallel",
"optimization"
] |
190 | 2 | null | 176 | 7 | null | It turned out that this task was quite easy to accomplish using [vis.js](http://visjs.org/). [This](http://visjs.org/examples/graph/20_navigation.html) was the best example code which I have found.
The example of what I have built upon this is [here](http://laboratoriumdanych.pl/jak-powstaje-siec/) (scroll to the botto... | null | CC BY-SA 3.0 | null | 2014-05-22T12:14:49.727 | 2014-05-22T12:14:49.727 | null | null | 173 | null |
191 | 1 | 194 | null | 8 | 1166 | Can someone explain me, how to classify a data like MNIST with MLBP-Neural network if I make more than one output (e.g 8), I mean if I just use one output I can easily classify the data, but if I use more than one, which output should I choose ?
| Multi layer back propagation Neural network for classification | CC BY-SA 3.0 | null | 2014-05-22T13:36:24.120 | 2014-06-10T08:38:27.093 | null | null | 273 | [
"neural-network"
] |
192 | 1 | null | null | 8 | 522 | The most popular use case seem to be recommender systems of different kinds (such as recommending shopping items, users in social networks etc.).
But what are other typical data science applications, which may be used in a different verticals?
For example: customer churn prediction with machine learning, evaluating cus... | What are the most popular data science application use cases for consumer web companies | CC BY-SA 3.0 | null | 2014-05-22T15:15:41.133 | 2014-05-23T06:03:40.577 | null | null | 88 | [
"usecase",
"consumerweb"
] |
193 | 2 | null | 192 | 4 | null | It depends, of course, on the focus of the company: commerce, service, etc. In adition to the use cases you suggested, some other use cases would be:
- Funnel analysis: Analyzing the way in which consumers use a website and complete a sale may include data science techniques, especially if the company operates at a l... | null | CC BY-SA 3.0 | null | 2014-05-22T15:43:57.160 | 2014-05-22T15:43:57.160 | null | null | 178 | null |
194 | 2 | null | 191 | 5 | null | Suppose that you need to classify something in K classes, where K > 2. In this case the most often setup I use is one hot encoding. You will have K output columns, and in the training set you will set all values to 0, except the one which has the category index, which could have value 1. Thus, for each training data se... | null | CC BY-SA 3.0 | null | 2014-05-22T19:20:14.130 | 2014-05-22T19:20:14.130 | null | null | 108 | null |
195 | 2 | null | 192 | 5 | null | Satisfaction is a huge one that I run into a lot. Huge referring to importance/difficulty/complexity.
The bottom line is that for very large services (search engines, facebook, linkedin, etc...) your users are simply a collection of log lines. You have little ability to solicit feed back from them (not a hard and fas... | null | CC BY-SA 3.0 | null | 2014-05-22T20:48:55.297 | 2014-05-23T06:03:40.577 | 2014-05-23T06:03:40.577 | 92 | 92 | null |
196 | 1 | 197 | null | 13 | 7379 | So we have potential for a machine learning application that fits fairly neatly into the traditional problem domain solved by classifiers, i.e., we have a set of attributes describing an item and a "bucket" that they end up in. However, rather than create models of probabilities like in Naive Bayes or similar classifie... | Algorithm for generating classification rules | CC BY-SA 3.0 | null | 2014-05-22T21:47:26.980 | 2020-08-06T11:04:09.857 | 2014-05-23T03:27:20.630 | 84 | 275 | [
"machine-learning",
"classification"
] |
197 | 2 | null | 196 | 10 | null | C45 made by Quinlan is able to produce rule for prediction. Check this [Wikipedia](http://en.wikipedia.org/wiki/C4.5_algorithm) page. I know that in [Weka](http://www.cs.waikato.ac.nz/~ml/weka/) its name is J48. I have no idea which are implementations in R or Python. Anyway, from this kind of decision tree you should... | null | CC BY-SA 3.0 | null | 2014-05-22T21:54:05.660 | 2014-05-22T21:59:22.117 | 2014-05-22T21:59:22.117 | 108 | 108 | null |
198 | 2 | null | 192 | 5 | null | Also, there seem to be a very comprehensive list of data science use cases by function and by vertical on Kaggle - ["Data Science Use Cases"](http://www.kaggle.com/wiki/DataScienceUseCases)
| null | CC BY-SA 3.0 | null | 2014-05-23T03:05:57.990 | 2014-05-23T03:05:57.990 | null | null | 88 | null |
199 | 1 | 202 | null | 25 | 33962 | LDA has two hyperparameters, tuning them changes the induced topics.
What does the alpha and beta hyperparameters contribute to LDA?
How does the topic change if one or the other hyperparameters increase or decrease?
Why are they hyperparamters and not just parameters?
| What does the alpha and beta hyperparameters contribute to in Latent Dirichlet allocation? | CC BY-SA 3.0 | null | 2014-05-23T06:25:50.480 | 2022-05-20T16:20:33.417 | null | null | 122 | [
"topic-model",
"lda",
"parameter"
] |
200 | 2 | null | 134 | 4 | null | You also can create a MongoDB-Hadoop [connection](http://docs.mongodb.org/ecosystem/tutorial/getting-started-with-hadoop/).
| null | CC BY-SA 3.0 | null | 2014-05-23T08:34:38.900 | 2014-05-23T08:34:38.900 | null | null | 278 | null |
201 | 2 | null | 155 | 76 | null | Update:
Kaggle.com, a home of modern data science & machine learning enthusiasts:), opened [it's own repository of the data sets](https://www.kaggle.com/datasets).
---
In addition to the listed sources.
Some social network data sets:
- Stanford University large network dataset collection (SNAP)
- A huge twitter da... | null | CC BY-SA 3.0 | null | 2014-05-23T09:09:44.490 | 2016-01-21T08:44:01.610 | 2017-04-13T12:44:20.183 | -1 | 97 | null |
202 | 2 | null | 199 | 22 | null | The Dirichlet distribution is a multivariate distribution. We can denote the parameters of the Dirichlet as a vector of size K of the form ~$\frac{1}{B(a)} \cdot \prod\limits_{i} x_i^{a_{i-1}}$, where $a$ is the vector of size $K$ of the parameters, and $\sum x_i = 1$.
Now the LDA uses some constructs like:
- a docume... | null | CC BY-SA 4.0 | null | 2014-05-23T13:47:54.603 | 2022-05-20T16:20:33.417 | 2022-05-20T16:20:33.417 | -1 | 108 | null |
203 | 2 | null | 189 | 2 | null | Never done stuff on that scale, but as no-one else has jumped in yet have you seen these two papers that discuss non-commercial solutions? Symphony and COIN-OR seem to be the dominant suggestions.
Linderoth, Jeffrey T., and Andrea Lodi. "MILP software." Wiley encyclopedia of operations research and management science ... | null | CC BY-SA 3.0 | null | 2014-05-23T14:28:41.563 | 2014-05-23T14:28:41.563 | null | null | 265 | null |
204 | 2 | null | 116 | 7 | null | I recently did a similar project in Python (predicting opinions using FB like data), and had good results with the following basic process:
- Read in the training set (n = N) by iterating over comma-delimited like records line-by-line and use a counter to identify the most popular pages
- For each of the K most popul... | null | CC BY-SA 4.0 | null | 2014-05-23T19:28:01.903 | 2020-08-20T18:51:34.423 | 2020-08-20T18:51:34.423 | 98307 | 250 | null |
205 | 1 | 208 | null | 12 | 1771 | Working on what could often be called "medium data" projects, I've been able to parallelize my code (mostly for modeling and prediction in Python) on a single system across anywhere from 4 to 32 cores. Now I'm looking at scaling up to clusters on EC2 (probably with StarCluster/IPython, but open to other suggestions as ... | Instances vs. cores when using EC2 | CC BY-SA 3.0 | null | 2014-05-23T19:45:54.283 | 2017-02-19T09:12:49.270 | null | null | 250 | [
"parallel",
"clustering",
"aws"
] |
206 | 2 | null | 205 | 6 | null | All things considered equal (cost, CPU perf, etc.) you could choose the smallest instance that can hold all of my dataset in memory and scale out. That way
- you make sure not to induce unnecessary latencies due to network communications, and
- you tend to maximize the overall available memory bandwidth for your pro... | null | CC BY-SA 3.0 | null | 2014-05-23T21:01:18.630 | 2014-05-23T21:01:18.630 | null | null | 172 | null |
207 | 2 | null | 205 | 11 | null | A general rule of thumb is to not distribute until you have to. It's usually more efficient to have N servers of a certain capacity than 2N servers of half that capacity. More of the data access will be local, and therefore fast in memory versus slow across the network.
At a certain point, scaling up one machine become... | null | CC BY-SA 3.0 | null | 2014-05-24T10:36:58.987 | 2014-05-24T10:36:58.987 | null | null | 21 | null |
208 | 2 | null | 205 | 11 | null | When using IPython, you very nearly don't have to worry about it (at the expense of some loss of efficiency/greater communication overhead). The parallel IPython plugin in StarCluster will by default start one engine per physical core on each node (I believe this is configurable but not sure where). You just run what... | null | CC BY-SA 3.0 | null | 2014-05-24T11:18:26.497 | 2017-02-19T09:12:49.270 | 2017-02-19T09:12:49.270 | 26 | 26 | null |
209 | 1 | 212 | null | 10 | 1421 | A recommendation system keeps a log of what recommendations have been made to a particular user and whether that user accepts the recommendation. It's like
```
user_id item_id result
1 4 1
1 7 -1
5 19 1
5 80 1
```
where 1 means the user accepted the recommendation while -1... | How should one deal with implicit data in recommendation | CC BY-SA 3.0 | null | 2014-05-25T13:57:52.657 | 2014-05-27T10:58:00.620 | 2014-05-26T05:12:32.653 | 71 | 71 | [
"recommender-system"
] |
210 | 2 | null | 199 | 13 | null | Assuming symmetric Dirichlet distributions (for simplicity), a low alpha value places more weight on having each document composed of only a few dominant topics (whereas a high value will return many more relatively dominant topics). Similarly, a low beta value places more weight on having each topic composed of only a... | null | CC BY-SA 3.0 | null | 2014-05-26T04:07:32.390 | 2014-05-26T04:07:32.390 | null | null | 283 | null |
211 | 1 | 213 | null | 9 | 4593 | I'm new to this community and hopefully my question will well fit in here.
As part of my undergraduate data analytics course I have choose to do the project on human activity recognition using smartphone data sets. As far as I'm concern this topic relates to Machine Learning and Support Vector Machines. I'm not well fa... | Human activity recognition using smartphone data set problem | CC BY-SA 4.0 | null | 2014-05-27T10:41:33.220 | 2020-08-17T03:25:03.437 | 2020-08-16T21:51:47.670 | 98307 | 295 | [
"bigdata",
"machine-learning",
"databases",
"clustering",
"data-mining"
] |
212 | 2 | null | 209 | 7 | null | Your system isn't just trained on items that are recommended right? if so you have a big feedback loop here. You want to learn from all clicks/views, I hope.
You suggest that not-looking at an item is a negative signal. I strongly suggest you do not treat it that way. Not interacting with something is almost always bes... | null | CC BY-SA 3.0 | null | 2014-05-27T10:58:00.620 | 2014-05-27T10:58:00.620 | null | null | 21 | null |
213 | 2 | null | 211 | 8 | null | The data set definitions are on the page here:
[Attribute Information at the bottom](http://archive.ics.uci.edu/ml/datasets/Human+Activity+Recognition+Using+Smartphones#)
or you can see inside the ZIP folder the file named activity_labels, that has your column headings inside of it, make sure you read the README carefu... | null | CC BY-SA 3.0 | null | 2014-05-27T12:07:45.920 | 2014-05-27T12:07:45.920 | null | null | 59 | null |
214 | 2 | null | 155 | 37 | null | The following links are available
- Public Data Sets
- Google Public Data Sets
- Amazon Web Services
- Finding Data on the Internet
| null | CC BY-SA 3.0 | null | 2014-05-27T16:05:02.883 | 2017-12-17T19:30:24.190 | 2017-12-17T19:30:24.190 | 28175 | 295 | null |
215 | 1 | null | null | 16 | 1055 | I'm building a workflow for creating machine learning models (in my case, using Python's `pandas` and `sklearn` packages) from data pulled from a very large database (here, Vertica by way of SQL and `pyodbc`), and a critical step in that process involves imputing missing values of the predictors. This is straightforwar... | Where in the workflow should we deal with missing data? | CC BY-SA 3.0 | null | 2014-05-27T21:07:48.973 | 2014-06-11T11:32:13.433 | null | null | 250 | [
"machine-learning",
"python",
"pandas",
"scikit-learn"
] |
216 | 2 | null | 215 | 15 | null | My strong opinion regarding automated tasks like imputation (but, here I can include also scaling, centering, feature selection, etc) is to avoid in any way do such things without carefully inspecting your data.
Of course, after deciding what kind of imputation to apply it can be automated (under the assumption that t... | null | CC BY-SA 3.0 | null | 2014-05-28T07:08:05.393 | 2014-05-28T07:08:05.393 | null | null | 108 | null |
217 | 2 | null | 211 | 5 | null | It looks like this (or very similar data set) is used for Coursera courses. Cleaning this dataset is task for [Getting and Cleaning Data](https://www.coursera.org/course/getdata), but it is also used for case study for [Exploratory Data analysis](https://class.coursera.org/exdata-002). Video from this case study is ava... | null | CC BY-SA 3.0 | null | 2014-05-28T09:43:54.197 | 2014-05-28T09:43:54.197 | null | null | 82 | null |
218 | 1 | null | null | 3 | 1714 | So, I have a dataset with 39.949 variables and 180 rows. dataset is successfully
saved in DataFrame but when I try to find cov() it result an error.
here is the code
```
import pandas as pd
cov_data=pd.DataFrame(dataset).cov()
```
Here is the error
```
File "/home/syahdeini/Desktop/FP/pca_2.py", line 44, in find_... | built-in cov in pandas DataFrame results ValueError array is too big | CC BY-SA 3.0 | null | 2014-05-29T13:08:09.060 | 2014-05-29T14:31:51.913 | null | null | 273 | [
"python",
"pandas"
] |
219 | 2 | null | 218 | 2 | null | Since you have 39,949 variables, the covariance matrix would have about 1.6 billion elements (39,949 * 39,949 = 1,595,922,601). That is likely why you are getting that error.
| null | CC BY-SA 3.0 | null | 2014-05-29T13:51:48.820 | 2014-05-29T13:51:48.820 | null | null | 178 | null |
220 | 2 | null | 218 | 6 | null | Christopher is right about the size of the array. To be simplistic about it, if this translates to 1.6B floats, at 16 bytes per float (32-bit version; 64-bit is bigger), then you're trying to create an array of about 26 GB. Even if you have the RAM for that, I'd imagine that it's probably going to overload something el... | null | CC BY-SA 3.0 | null | 2014-05-29T14:13:00.317 | 2014-05-29T14:31:51.913 | 2014-05-29T14:31:51.913 | 250 | 250 | null |
221 | 2 | null | 196 | 8 | null | It's actually even simpler than that, from what you describe---you're just looking for a basic classification tree algorithm (so no need for slightly more complex variants like C4.5 which are optimized for prediction accuracy). The canonical text is [this](https://rads.stackoverflow.com/amzn/click/com/0412048418).
This... | null | CC BY-SA 4.0 | null | 2014-05-29T14:30:21.357 | 2020-08-06T11:03:53.690 | 2020-08-06T11:03:53.690 | 98307 | 250 | null |
222 | 2 | null | 155 | 22 | null | [Enigma](http://enigma.io) is a repository of public available datasets. Its free plan offers public data search, with 10k API calls per month. Not all public databases are listed, but the list is enough for common cases.
I used it for academic research and it saved me a lot of time.
---
Another interesting source o... | null | CC BY-SA 3.0 | null | 2014-05-29T19:02:13.210 | 2014-05-30T21:05:52.147 | 2014-05-30T21:05:52.147 | 43 | 43 | null |
223 | 1 | null | null | 23 | 3690 | Having a lot of text documents (in natural language, unstructured), what are the possible ways of annotating them with some semantic meta-data? For example, consider a short document:
```
I saw the company's manager last day.
```
To be able to extract information from it, it must be annotated with additional data to b... | How to annotate text documents with meta-data? | CC BY-SA 3.0 | null | 2014-05-29T20:11:16.327 | 2020-07-02T13:04:00.943 | null | null | 227 | [
"nlp",
"metadata",
"data-cleaning",
"text-mining"
] |
224 | 1 | null | null | 4 | 342 | The output of my word alignment file looks as such:
```
I wish to say with regard to the initiative of the Portuguese Presidency that we support the spirit and the political intention behind it . In bezug auf die Initiative der portugiesischen Präsidentschaft möchte ich zum Ausdruck bringen , daß wir den Geist und die ... | How to get phrase tables from word alignments? | CC BY-SA 3.0 | null | 2014-05-31T14:28:42.317 | 2018-05-06T22:11:50.250 | 2018-05-06T22:11:50.250 | 25180 | 122 | [
"machine-translation"
] |
226 | 2 | null | 155 | 16 | null | I've found this link in Data Science Central with a list of free datasets: [Big data sets available for free](http://www.datasciencecentral.com/profiles/blogs/big-data-sets-available-for-free)
| null | CC BY-SA 3.0 | null | 2014-05-31T19:59:15.563 | 2014-05-31T19:59:15.563 | null | null | 290 | null |
227 | 1 | 242 | null | 12 | 7178 | Can someone kindly tell me about the trade-offs involved when choosing between Storm and MapReduce in Hadoop Cluster for data processing? Of course, aside from the obvious one, that Hadoop (processing via MapReduce in a Hadoop Cluster) is a batch processing system, and Storm is a real-time processing system.
I have wor... | Tradeoffs between Storm and Hadoop (MapReduce) | CC BY-SA 3.0 | null | 2014-06-01T10:25:51.163 | 2014-06-10T23:33:28.443 | 2014-06-01T21:59:02.347 | 339 | 339 | [
"bigdata",
"efficiency",
"apache-hadoop",
"distributed"
] |
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