README updated.

README.md

@@ -6,6 +6,8 @@ language:
 - en
 size_categories:
 - 100K<n<1M
+source_datasets:
+- original
 configs:
 - config_name: default
   data_files:
@@ -17,4 +19,22 @@ configs:
     path: "test.zip"
 ---
 ## Dataset Description
-The text data (title and abstract) of 164230 arXiv preprints which are associated with at least one MSC (mathematical subject classification) code. Predicting 3-character MSC codes based on the cleaned text (processed title+abstarct) amounts to a multi-label classification task.
+The text data (title and abstract) of 164230 arXiv preprints which are associated with at least one [MSC (mathematical subject classification)](https://en.wikipedia.org/wiki/Mathematics_Subject_Classification) code. Predicting 3-character MSC codes based on the cleaned text (processed title+abstarct) amounts to a multi-label classification task.
+
+## Dataset Structure
+- The column `cleaned_text` should be used as the input of the text classification task. This is obtained from processing the text data (titles and abstracts) of math-related preprints.
+- The last 531 columns are one-hot encoded MSC classes, and should be used as target variables of the multi-lable classification task.
+- Other columns are auxiliary and contain URLs, the original titles and abstracts, and the primary arXiv category.
+
+
+## Data Splits
+Stratified sampling was used for splitting the data so that the proportions of a target variable among the splits are not very different. 
+
+|Dataset  |Description       |Number of instances  |
+|---------|------------------|---------------------|
+|main.zip |the whole data    |164230               |
+|train.zip|the training set  |104675               |
+|val.zip  |the validation set|18540                |
+|test.zip |the test set      |41015                |
+
+## Data Collection