Multiple rows share a value in a column, how do I put all of these rows into one single row?
I'm working with a text file that looks something like this:
rs001 EEE /n rs008 EEE /n rs3开发者_开发知识库45 EEE /n rs542 CHG /n re432 CHG /n
I want to be able to collapse all of the rows that share the same value in column 2 into one single row (for example, rs001 rs008 rs345 EEE
). Is there an easy way to do this using unix text processing or python?
Thanks
#!/usr/bin/env python
from __future__ import with_statement
from itertools import groupby
with open('file','r') as f:
# We define "it" to be an iterator, for each line
# it yields pairs like ('rs001','EEE')
it=(line.strip().split() for line in f)
# groupby does the heave work.
# lambda p: p[1] is the keyfunction. It groups pairs according to the
# second element, e.g. 'EEE'
for key,group in groupby(it,lambda p: p[1]):
# group might be something like [('rs001','EEE'),('rs008','EEE'),...]
# key would be something like 'EEE', the value that we're grouping by.
print('%s %s'%(' '.join([p[0] for p in group]),key))
here's gawk for you
$ awk '{a[$2]=a[$2]FS$1}END{for(i in a)print i,a[i]}' file
EEE rs001 rs008 rs345
CHG rs542 re432
One option is to build a dictionary keyed on the column 2 data:
from collections import defaultdict #defaultdict will save a line or two of code
d = defaultdict(list) # goal is for d to look like {'EEE':['rs001', 'rs008', ...
for line in file('data.txt', 'r'):
v, k = line.strip().split()
d[k].append(v)
for k, v in d.iteritems(): # print d as the strings you want
print ' '.join(v+[k])
This approach has the advantage that it doesn't require the column 2 terms to be grouped together (though whether or not column 2 is pre-grouped is not directly specified in the question).
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