Extract numbers from a string list - python

Question

If I have a list like this [ [100], [500], [300] ], what's the best way in python to extract the numbers from it?

result = [ 100, 500, 300 ]

score 3 · Answer 1 · answered Mar 15 '12 at 00:44

3

x = [ [100] , [500] , [300] ]
y = [ i[0] for i in x]

#or
from itertools import chain
y = list(chain.from_iterable(x))

answered Mar 15 '12 at 00:44

kev

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Or (equivalent to the first) `import operator; y = map(operator.itemgetter(0), x)` :-) – ephemient Mar 15 '12 at 01:01

score 2 · Accepted Answer · edited May 23 '17 at 11:56

From this question:

l=[[100], [500], [300]]
result=[item for sublist in l for item in sublist]

From wikibooks:

def flatten(seq, list = None):
    """flatten(seq, list = None) -> list

    Return a flat version of the iterator `seq` appended to `list`
    """
    if list == None:
        list = []
    try:                          # Can `seq` be iterated over?
        for item in seq:          # If so then iterate over `seq`
            flatten(item, list)      # and make the same check on each item.
    except TypeError:             # If seq isn't iterable
        list.append(seq)             # append it to the new list.
    return list

Google is your friend ...

well, I did it like that: result = [ i[1:len(i)-1] for i in l] thanks :) — Vanddel, Mar 15 '12 at 00:54

Extract numbers from a string list - python

2 Answers2