create dictionary from csv file using a key within row in python

Question

How would i create a dictionary using a csv file if the key is the last index ( index[9] ) in every row. for example:

,,,,,,,,,KEY_1
,,,,,,,,,KEY_1
,,,,,,,,,KEY_1
,,,,,,,,,KEY_2
,,,,,,,,,KEY_2
,,,,,,,,,KEY_2
,,,,,,,,,KEY_3
,,,,,,,,,KEY_3
,,,,,,,,,KEY_3

Is there a way to create a dictionary that would look like this:

dictt = {
        'KEY_1':[,,,,,,,,], [,,,,,,,,], [,,,,,,,,],
        'KEY_2':[,,,,,,,,], [,,,,,,,,], [,,,,,,,,],
        'KEY_3':[,,,,,,,,], [,,,,,,,,], [,,,,,,,,],
        }

I only have 6mons of self taught python and I am working out the growing pains. Any help is greatly appreciated. thank you in advanced

Answer 1

In answer to your "is it possible" question, one must say "not quite", because no Python construct matches the syntax you show:

dictt = {
    'KEY_1':[,,,,,,,,], [,,,,,,,,], [,,,,,,,,],
    'KEY_2':[,,,,,,,,], [,,,,,,,,], [,,,,,,,,],
    'KEY_3':[,,,,,,,,], [,,,,,,,,], [,,,,,,,,],
    }

Entering this would be a syntax error, and no code can thus build the equivalent.

But if you actually mean, eg,

dictt = {
    'KEY_1':[['','',,,,,,,], [,,,,,,,,], [,,,,,,,,]],
    'KEY_2':[[,,,,,,,,], [,,,,,,,,], [,,,,,,,,]],
    'KEY_3':[[,,,,,,,,], [,,,,,,,,], [,,,,,,,,]],
    }

(and so on replacing each ,, to have something inside, eg an empty string -- not gonna spend a long time editing this to fix it!-), then sure, it is possible.

Eg:

import collections
import csv

dictt = collections.defaultdict(list)

with open('some.csv') as f:
    r = csv.reader(f)
    for row in r:
        dictt[r[-1]].append(r[:-1])

When this is done dictt will be an instance of collections.defaultdict (a subclass of dict ) but you can use it as a dict . Or if you absolutely insist on its being a dict and not a subclass thereof (though there is no conceivably good reason to thus insist), follow up with

dictt = dict(dictt)

and voila, it's converted:-)

Answer 2

Another way:

txt='''\
,,,,,,,,,KEY_1
,,,,,,,,,KEY_1
,,,,,,,,,KEY_1
,,,,,,,,,KEY_2
,,,,,,,,,KEY_2
,,,,,,,,,KEY_2
,,,,,,,,,KEY_3
,,,,,,,,,KEY_3
,,,,,,,,,KEY_3
'''

import csv

result={}
for line in csv.reader(txt.splitlines()):
    result.setdefault(line[-1], []).append(line[:-1])

>>> result
{'KEY_1': [['', '', '', '', '', '', '', '', ''], ['', '', '', '', '', '', '', '', ''], ['', '', '', '', '', '', '', '', '']], 'KEY_3': [['', '', '', '', '', '', '', '', ''], ['', '', '', '', '', '', '', '', ''], ['', '', '', '', '', '', '', '', '']], 'KEY_2': [['', '', '', '', '', '', '', '', ''], ['', '', '', '', '', '', '', '', ''], ['', '', '', '', '', '', '', '', '']]}