python group list items by string matching pattern

Question

I need to group similar items like this:

['bty_char_rick_10', 'shd_char_rick_10', 'refl_char_rick_10', 'spec_char_rick_10'], ['bty_char_toby_01', 'shd_char_toby_01'], ['bty_prop_item_01', 'shd_prop_item_01'] ...]

been sweeping the whole internet but can't find anything regarding string operations. should be a simple fnmatch or string match but I can't get it to work.

from itertools import groupby

lst = ['bty_char_rick_10', 'bty_char_toby_01', 'bty_prop_chair_20', 'bty_prop_item_01', 'bty_prop_vase_10', 'bty_vhcl_tessla_10', 'occ_prop_vase_10', 'refl_char_rick_10', 'refl_prop_vase_10', 'shd_char_rick_10', 'shd_char_toby_01', 'shd_prop_chair_20', 'shd_prop_item_01', 'shd_prop_vase_10', 'shd_vhcl_tessla_10', 'spec_char_rick_10']

keyf = lambda text: text.split('_')[1]+'_'+text.split('_')[2]
print [list(items) for gr, items in groupby(sorted(lst), key=keyf)]

Austin · Accepted Answer · 2019-08-23 02:16:59Z

You need to sort the list by the same key:

[list(g) for k, g in groupby(sorted(lst, key=f), key=f)]

where f is:

f = lambda x: x.split('_')[1:]

Example:

from itertools import groupby

lst = ['bty_char_rick_10', 'bty_char_toby_01', 'bty_prop_chair_20', 'bty_prop_item_01',
       'bty_prop_vase_10', 'bty_vhcl_tessla_10', 'occ_prop_vase_10', 'refl_char_rick_10',
       'refl_prop_vase_10', 'shd_char_rick_10', 'shd_char_toby_01', 'shd_prop_chair_20',
       'shd_prop_item_01', 'shd_prop_vase_10', 'shd_vhcl_tessla_10', 'spec_char_rick_10']

f = lambda x: x.split('_')[1:]    
print([list(g) for k, g in groupby(sorted(lst, key=f), key=f)])

# [['bty_char_rick_10', 'refl_char_rick_10', 'shd_char_rick_10', 'spec_char_rick_10'],
#  ['bty_char_toby_01', 'shd_char_toby_01'],
#  ['bty_prop_chair_20', 'shd_prop_chair_20'],
#  ['bty_prop_item_01', 'shd_prop_item_01'],
#  ['bty_prop_vase_10', 'occ_prop_vase_10', 'refl_prop_vase_10', 'shd_prop_vase_10'],
#  ['bty_vhcl_tessla_10', 'shd_vhcl_tessla_10']]

RoadRunner · Accepted Answer · 2019-08-23 03:00:49Z

Your proposed solution is O(nlogn) due to sorting. An O(n) solution would be just to use a collections.defaultdict:

from collections import defaultdict

lst = ['bty_char_rick_10', 'bty_char_toby_01', 'bty_prop_chair_20', 'bty_prop_item_01',
       'bty_prop_vase_10', 'bty_vhcl_tessla_10', 'occ_prop_vase_10', 'refl_char_rick_10',
       'refl_prop_vase_10', 'shd_char_rick_10', 'shd_char_toby_01', 'shd_prop_chair_20',
       'shd_prop_item_01', 'shd_prop_vase_10', 'shd_vhcl_tessla_10', 'spec_char_rick_10']

d = defaultdict(list)
for string in lst:
    _, key = string.split("_", 1)
    d[key].append(string)

print(list(d.values()))

Output:

[['bty_char_rick_10', 'refl_char_rick_10', 'shd_char_rick_10', 'spec_char_rick_10'], ['bty_char_toby_01', 'shd_char_toby_01'], ['bty_prop_chair_20', 'shd_prop_chair_20'], ['bty_prop_item_01', 'shd_prop_item_01'], ['bty_prop_vase_10', 'occ_prop_vase_10', 'refl_prop_vase_10', 'shd_prop_vase_10'], ['bty_vhcl_tessla_10', 'shd_vhcl_tessla_10']]

Collectives™ on Stack Overflow

python group list items by string matching pattern

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related