How To Split A List Into Subsets Based On A Pattern?
I'm doing this but it feels this can be achieved with much less code. It is Python after all. Starting with a list, I split that list into subsets based on a string prefix. # Split
Solution 1:
You could use itertools.groupby
:
>>>import itertools>>>mylist = ['sub_0_a', 'sub_0_b', 'sub_1_a', 'sub_1_b']>>>for k,v in itertools.groupby(mylist,key=lambda x:x[:5]):...print k, list(v)...
sub_0 ['sub_0_a', 'sub_0_b']
sub_1 ['sub_1_a', 'sub_1_b']
or exactly as you specified it:
>>> [list(v) for k,v in itertools.groupby(mylist,key=lambda x:x[:5])]
[['sub_0_a', 'sub_0_b'], ['sub_1_a', 'sub_1_b']]
Of course, the common caveats apply (Make sure your list is sorted with the same key you're using to group), and you might need a slightly more complicated key function for real world data...
Solution 2:
In [28]: mylist = ['sub_0_a', 'sub_0_b', 'sub_1_a', 'sub_1_b']
In [29]: lis=[]
In [30]: for x in mylist:
i=x.split("_")[1]
try:
lis[int(i)].append(x)
except:
lis.append([])
lis[-1].append(x)
....:
In [31]: lis
Out[31]: [['sub_0_a', 'sub_0_b'], ['sub_1_a', 'sub_1_b']]
Solution 3:
Use itertools
' groupby
:
def get_field_sub(x): return x.split('_')[1]
mylist = sorted(mylist, key=get_field_sub)
[ (x, list(y)) for x, y in groupby(mylist, get_field_sub)]
Post a Comment for "How To Split A List Into Subsets Based On A Pattern?"