[Tutor] Help merge files using python

[Peter Otten]

jarod_v6 at libero.it wrote:

> Hi I want to merge many files like this:
> #file1
> A	10
> B	20
> C	30
> #file2
> B	45
> Z	10
> #file1
> A	60
> B	70
> C	10
> 
> I want to obtain
> 
> A 10 0 60
> B 20 45 70
> C 30 0 10
> Z 0 10 0
> 
> I try to do like this:
>  f = os.listdir(".")
> for i in f:
>  T =open(i,"r")
> for r in t.readlines():
> print r
> 
> Could you please help me to understand how to use the right procedure in
> python?Thanks a lot!

If I were into spoon-feeding I would post

import os

folder = "."
destfilename = "../pivot"

filenames = sorted(os.listdir(folder))
filenames = [os.path.join(folder, name) for name in filenames]
N = len(filenames)

pivot = {}
for index, filename in enumerate(filenames):
    with open(filename) as file:
        for line in file:
            key, value = line.split()
            pivot.setdefault(key, ["0"] * N)[index] = value

with open(destfilename, "w") as dest:
    for key, value in sorted(pivot.items()):
        dest.write("\t".join([key] + value))
        dest.write("\n")