[Tutor] Script to collect values from .csv

[Prasad, Ramit]

> I have a very large .csv (correlationfile, which is 16 million lines long)
> which I want to split into smaller .csvs. The smaller csvs should be created
> be searching for a value and printing any line which contains that value - all
> these values are contained in another .csv (vertexfile). I think that I have
> an indentation problem or have made a mistake with my loops because I only get
> data in one of the output .csvs (outputfile) which is for the first one of the
> values. The other .csvs are empty.
> 
> Can somebody help me please?
> 
> Thanks so much!
> 
> Emma
> 
> import os
> path = os.getcwd()
> x = ''
> for v in vertexfile:
>     vs = v.replace('\n','')
>     outputfile = open(os.path.join(path,vs+'.csv'),'w')
>     for c in correlationfile:
>         cs = c.replace('\n','').split(',')
>         if vs == cs[0]: print vs
>     outputfile.write(x)
> outputfile.close()

Indent the outputfile.close()  to be inside the for loop.
That should fix your problem.

I would recommend working with csv module instead. No need
to worry about replacing new lines or if a comma is contained 
inside your data. Note, when using the csv module open the 
files as 'rb' and 'wb'.


Ramit


Ramit Prasad | JPMorgan Chase Investment Bank | Currencies Technology
712 Main Street | Houston, TX 77002
work phone: 713 - 216 - 5423

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