python intersect of dict items

问题

ok another python question...

I have a dict:

aDict[1] = '3,4,5,6,7,8'
aDict[5] = '5,6,7,8,9,10,11,12'
aDict[n] = '5,6,77,88'

n could be any limit but the keys are not in sequence.

How do I extract the intersect of the csv'd items? So in this case the answer would be '5,6'.

Thanks

回答1:

from functools import reduce # if Python 3

reduce(lambda x, y: x.intersection(y), (set(x.split(',')) for x in aDict.values()))

回答2:

First of all, you need to convert these to real lists.

l1 = '3,4,5,6,7,8'.split(',')

Then you can use sets to do the intersection.

result = set(l1) & set(l2) & set(l3)

回答3:

Python Sets are ideal for that task. Consider the following (pseudo code):

intersections = None
for value in aDict.values():
    temp = set([int(num) for num in value.split(",")])
    if intersections is None:
        intersections = temp
    else:
        intersections = intersections.intersection(temp)

print intersections

回答4:

result = None
for csv_list in aDict.values():
    aList = csv_list.split(',')
    if result is None:
        result = set(aList)
    else:
        result = result & set(aList)
print result

回答5:

Since set.intersection() accepts any number of sets, you can make do without any use of reduce():

set.intersection(*(set(v.split(",")) for v in aDict.values()))

Note that this version won't work for an empty aDict.

If you are using Python 3, and your dictionary values are bytes objects rather than strings, just split at b"," instead of ",".

来源：https://stackoverflow.com/questions/7765583/python-intersect-of-dict-items

标签

python

intersect