Concatenate tab-delimited txt files vertically

Question

input1, input2, output are tab-delimited txt files.

If input1 is

a b c
1 2 3

and input2 is

e r t

then I would want output to be

a b c
1 2 3
e r t

I tried to concatenate files using python by learning from Python concatenate text files

I tried

filenames = ['input1.txt', 'input2.txt']
with open('output.txt', 'w') as outfile:
    for fname in filenames:
        with open(fname) as infile:
            for line in infile:
                outfile.write(line)

and then tried

filenames = ['input1.txt', 'input2.txt']
import fileinput
    with open('output.txt', 'w') as fout:
    for line in fileinput.input(filenames):
        fout.write(line)

But both codes concatenate files horizontally, not vertically.

The codes create this:

a b c
1 2 3e r t

I am not sure I follow you; `input1` and `input2` are *concatenated*; the code samples you shared **also** concatenate the files. — Martijn Pieters, Jul 13 '14 at 12:02
replace `outfile.write(line)` with `outfile.write(line + '\n')` — Korem, Jul 13 '14 at 12:03
`cat input1 input2 > output` would also do what you want in this case. This is precisely what concatenation is supposed to accomplish. — Two-Bit Alchemist, Jul 13 '14 at 12:05
@Korem I tried that, but it created another incorrect output. It adds unnecessary line break. — user3123767, Jul 13 '14 at 12:10
@user3123767: no, that's a UNIX / Linux command line to be entered into your shell. — Martijn Pieters, Jul 13 '14 at 12:12
@user3123767 Martijn Peters is correct -- will also work if you are on a Mac (basically only Windows cannot do this AFAIK). — Two-Bit Alchemist, Jul 13 '14 at 15:59

score 4 · Accepted Answer · answered Jul 13 '14 at 12:10

4

The problem of your input files is, that the last line is not terminated by a new-line-character. So you have to add it by hand:

filenames = ['input1.txt', 'input2.txt']
with open('output.txt', 'w') as outfile:
    for fname in filenames:
        with open(fname) as infile:
            outfile.write(infile.read().rstrip() + '\n')

answered Jul 13 '14 at 12:10

Daniel

42,087
4
55
81

I explained my problem at http://stackoverflow.com/questions/24936955/python-vertical-txt-concatenation-not-working-properly Could you have a look at it? – user3123767 Jul 24 '14 at 14:48

Leth0_ · Answer 2 · 2014-07-13T12:14:54.517

1

You need to line break using \n. Try the following code sample,

filenames = ['input1.txt', 'input2.txt']
with open('output.txt', 'w') as outfile:
    for fname in filenames:
        with open(fname) as infile:
            for line in infile:
                outfile.write(line)
        outfile.write("\n")

edited Jul 13 '14 at 12:14

answered Jul 13 '14 at 12:04

Leth0_

544
2
6
15

@Letho0_ I tried that, but it created another incorrect output. It adds unnecessary line break. – user3123767 Jul 13 '14 at 12:07
1 d e \r\n\r\n e g h \r\n 4 4 3 – user3123767 Jul 13 '14 at 12:08
1

adds unnecessary newlines to every line. – Daniel Jul 13 '14 at 12:11
@Leth0_ I explained my problem at http://stackoverflow.com/questions/24936955/python-vertical-txt-concatenation-not-working-properly Could you have a look at it? – user3123767 Jul 24 '14 at 14:47

Concatenate tab-delimited txt files vertically

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