Tim Chase
12/29/2007 3:23:00 PM
> A 1
> A 2
> A 3
> B 1
> C 2
> D 3
> D 4
> The result should be
>
> A 1|2|3
> B 1
> C 2
> D 3|4
>
> What should I do to get my results
Well, it depends on whether the resulting order matters. If not,
you can use KM's suggestion of a dictionary:
results = {}
for line in file('in.txt'):
k,v = line.rstrip('\n').split('\t')
results.setdefault(k, []).append(v)
for k,v in results.iteritems():
print k, '|'.join(v)
If, however, order matters, you have to do it in a slightly
buffered manner. It makes a difference when your input looks like
A 1
B 2
A 3
which should yield its own input, rather than "A 1|3". In this case
last_key = ''
values = []
for line in file('in.txt'):
k,v = line.rstrip('\n').split('\t')
if last_key != k:
if last_key:
print last_key, '|'.join(values)
last_key = k
values = [v]
else:
values.append(v)
if last_key:
print last_key, '|'.join(values)
should do the job. Which, if you like, can be reduced to a sed
one-liner
sed ':a;N;s/^\([^\t]\+\)\(.*\)\n\1\t\+\(.*\)/\1\2|\3/;ta;P;D'
....if it doesn't make your modem hang up on you, or if line-noise
assembly-language is your thing ;)
-tkc