Taking multiple lines of strings as command line input in Python

Question

In coding contests, I am supplied an initialization file from which to read initial parameters. However, sometimes the parameters are spread over separate lines as follows:

x
a 
b

(All of them integers)

Now when I read line1, I believe I would store x like this:

x = int(sys.argv[1])

How do I take care of other lines? Will sys.argv[2] give me the next parameter on line 2?

More precisely, will using:

par_list = sys.argv[1:].split(" ")

give me a list of parameters on all the lines?

timgeb · Accepted Answer · 2014-06-28 18:30:10Z

4

This will do the trick:

>> python program.py $(cat input.txt)

Sample program:

import sys
paras = [int(x) for x in sys.argv[1:]]
print(paras)

Sample input file:

42
-1
100

Output:

>> python program.py $(cat input.txt)
[42, -1, 100]

edited Jun 28, 2014 at 18:30

answered Jun 28, 2014 at 18:24

timgeb

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1 Comment

EGS Over a year ago

This only works in unix environments, and would not work on windows systems. @arvindch's answer should be the one accepted.

timgeb · Accepted Answer · 2014-06-28 18:33:42Z

3

I'm assuming you're passing the input filename to the python script, in cmdline.

python script.py input.txt

In which case, sys.argv[1] = 'input.txt' is to access the contents of the input file:

with open(sys.argv[1], 'r') as f:
    lines = f.readlines()

Now, lines is a list containing all the lines of data from input.txt.

edited Jun 28, 2014 at 18:33

timgeb

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answered Jun 28, 2014 at 17:49

arvindch

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1 Comment

pratik_m Over a year ago

Yes, that seems to be what I was looking for. Thank you!

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