I have a program that takes an input file:
python subprogram.py < input.txt > out.txt
If I have a number of input files, how can I write a single python program runs on those inputs and produces a single output? I believe the program should run like:
python program.py < input_1.txt input_2.txt > out.txt
And the program itself should look something like:
from subprogram import MyClass
import sys
if __name__ == '__main__':
myclass = MyClass()
myclass.run()
Have a look at the fileinput module
import fileinput
for line in fileinput.input():
process(line)
This iterates over the lines of all files listed in sys.argv[1:], defaulting to sys.stdin if the list is empty. If a filename is '-', it is also replaced by sys.stdin. To specify an alternative list of filenames, pass it as the first argument to input(). A single file name is also allowed.
Make your program accept command line parameters:
python program.py input_1.txt input_2.txt > out.txt
And you can access them like:
from subprogram import MyClass
import sys
if __name__ == '__main__':
class = MyClass()
class.run(sys.argv)
The way you're using is not about Python, it's about your shell. You are just redirect standart input/output to files. If you want to achieve that:
cat input1.txt input2.txt | python subprogram.py > out.txt
Let your shell do the work for you:
cat input_1.txt input_2.txt | python program.py > out.text
The cat command will concatenate the two input files together and your python program can just read from stdin and treat them like one big file.
<and>modifiers can have one file specified only, not a list of files.