dictionary from csv file python

Question

I have read a cvs file and I would like to create a dictionary from the information I have on that file. I´ve tried to use class csv.DictReader to that propose but it didnt gave me the results i wanted.

Now i am reading the file like this:

size_reader = csv.reader(f,dialect='excel-tab')

and I have as result this:

['chr1', '249250621']
['chr2', '243199373']
['chr3', '198022430']
['chr4', '191154276']
['chr5', '180915260']

I would like to make a dictionary with this structure:

dict ['chr4'] = 191154276
dict ['chr5'] = 180915260
dict ['chr2'] = 243199373

I tried regular expressions to split the elements the lines on the file but I had no success with it, maybe i used the wrong characters in the split function. Could you give some suggestion of how to separate the elements and built the dictionary?

Martijn Pieters · Accepted Answer · 2012-12-05 14:33:48Z

5

Just convert it to a dict directly:

 result = dict(size_reader)

This takes each two-column result from your size_reader CVS reader and uses that as the key and value for a python dictionary.

To convert each value to integers, you'd need to use a dict comprehension to process each value:

result = {k: int(v) for k, v in size_reader}

edited Dec 5, 2012 at 14:33

answered Dec 5, 2012 at 14:27

Martijn Pieters

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3 Comments

Martijn Pieters Over a year ago

@JonClements: Note to self: {k: v for k, v in iterable} == dict(iterable).. Thanks.

Martijn Pieters Over a year ago

@JonClements: Want to write an answer too? :-P

Jon Clements Over a year ago

sure - but I don't think "See Martijn's answer" is a valid answer ;)

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