I have multiple files with thousands of rows that I need to compare.
for example I want to do subtraction file3 = file2 - file1,
file1
1 10 5
2 20 4
3 30 3
file2
5 20 10
6 30 10
7 40 10
file3 would be
4 10 5
4 10 6
4 10 7
I wonder what is the best way to do this type of calculations. I am trying Python, but I am having a hard time to read the file to python to make it the proper kind of array for calculation. Thanks.
You could use numpy.genfromtxt:
import numpy as np
a1 = np.genfromtxt('file1')
a2 = np.genfromtxt('file2')
a3 = a2 - a1
print(a3)
array([[ 4., 10., 5.],
[ 4., 10., 6.],
[ 4., 10., 7.]])
Then you could save that array with numpy.savetxt with format %d if you need output as integers:
np.savetxt('file3', a3, fmt='%d')
Open both files, then loop through them with zip:
with open('file1.txt') as first, open('file2.txt') as second, open('file3.txt', 'w') as output:
for a, b in zip(first, second):
a = map(int, a.split())
b = map(int, b.split())
output.write(' '.join(map(str, (y-x for x,y in zip(a,b)))) + '\n')
