Question

I need to combine values in second column of a tab delimited file based on the ids in first column. The example is given below. What is the fastest way to do this. I can do it using for loop, going through each line, but I am sure there is some smart way to do it, which I am not aware of.

596230  Other postop infection
596230  Disseminated candidiasis
596230  Int inf clstrdium dfcile
596230  Pressure ulcer, site NOS
2846079 Schizophrenia NOS-unspec
7800713 CHF NOS
7800713 Chr airway obstruct NEC
7800713 Polymyalgia rheumatica
7800713 DMII wo cmp nt st uncntr

into

596230  Other postop infection, Disseminated candidiasis, Int inf clstrdium dfcile, Pressure ulcer, site NOS
2846079 Schizophrenia NOS-unspec
7800713 CHF NOS, Chr airway obstruct NEC, Polymyalgia rheumatica, DMII wo cmp nt st uncntr

Answer 1

Assuming you have your text in a file:

from collections import defaultdict
items = defaultdict(list)
with open("myfile.txt") as infile:
    for line in file:
        id, text = line.rstrip().split("\t")
        items[id].append(text)
for id in items:
    print id + "\t" + ", ".join(items[id])

This does not keep the original order of your ids, but it does keep the order of the texts.