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element because remember we start
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indexing at zero in Python and one is
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going to be the second second element so
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let me go ahead and run this now and see
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what happens python of uh
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students.pi enter and we see Hermione's
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in Gryffindor Harry's and Gryffindor Ron
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is in Gryffindor and Draco is in
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Slytherin so we have now implemented our
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own code from scratch that actually
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parses that is reads and interprets a
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CSV file ultimately here
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now let me pause to see if there's any
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questions but we'll make this even
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easier to read in just a moment
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any questions on what we've just done
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here by splitting by comma so my
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question is uh can we edit any line of
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code anytime we want or uh the only
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option that we have is to append uh the
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lines or let's say if we want to let's
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say change headies uh house to let's say
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Slytherin or some other house yeah a
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really good question what if you want to
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in Python change a line in the file and
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not just a pen to the end you would have
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to implement that logic yourself so for
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instance you could imagine now opening
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the file and reading all of the contents
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in then maybe iterating over each of
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those lines and as soon as you see that
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the current name equals equals Harry you
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could maybe change his house to
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Slytherin and then it would be up to you
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though to write all of those changes
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back to the file so in that case you
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might want to in simplest form read the
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file once and let it close then open it
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again but open for writing and change
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the whole file it's not really possible
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or easy to go in and change just part of
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the file though you can do it it's
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easier to actually read the whole file
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make your changes in memory then write
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the whole file out but for larger files
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where that might be quite slow you can
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be more clever than that well let me
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propose now that we clean this up a
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little bit because I actually think this
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is a little cryptic to read Row Bracket
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zero Row Bracket one it's it's not that
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well written at the moment I would say
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but it turns out that when you have a
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variable that's a list like row you
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don't have to throw all of those
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variables into a list you can actually
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unpack that whole sequence at once that
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is to say if you know that a function
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like split returns a list but you know
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in advance that it's going to return two
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values in a list the first and the
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second you don't have to throw them all
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into a variable that itself is a list
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you can actually unpack them
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simultaneously into two variables doing
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name comma house so this is a nice
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python technique to not only create but
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assign
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automatically in parallel two variables
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at once rather than just one so this
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will have the effect of putting the name
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in the left Hermione and it will have
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the effect of putting Gryffindor the
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house in the right variable and we now
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no longer have a row we can now make our
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code a little more readable by now
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literally just saying name down here and
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for instance house down here so just a
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little more readable even though
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functionally the code now is exactly the
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same
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all right so this now works and I'll
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confirm as much by just running it once
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more python of students.pi enter and we
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see that the text is as intended but
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suppose for the sake of discussion that
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I'd like to sort this list of output I'd
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like to say hello again to Draco first
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then hello to Harry then Hermione then
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Ron how can I go about doing this well
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let's take some inspiration from the
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previous example where we're only
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dealing with names and instead do it
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with these full phrases so and so is
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in-house well let me go ahead and do
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this I'm going to go ahead and start
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scratch and give myself a list called
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students equal to an empty list
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initially and then with open
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students.csv
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