4.7  3.9  5.9  6.2  6.6   6.6   6.5  4.7  5.5  11.2
21.9 12.4  5.6  4.5  5.8  6.7  5.4 3.6 3.9 0.7 0.8

File 1:
1 2 3 4 5

File 2:
5 4 3 2 1

File 3:
0 3 0 3 0

Array = {1,2,3,4,5}

Array = {1+5, 2+4, 3+3, 4+2, 5+1} = {6, 6, 6, 6, 6}

Array = {6+0, 6+3, 6+0, 6+3, 6+0} = {6, 9, 6, 9, 6}

Result = {6/3, 9/3, 6/3, 9/3, 6/3} = {2,3,2,3,2}

import os
flist = os.listdir(fdir)

import numpy as np
numbers = [] #list of files numbers lists
for text in flist:
with open(filename,'r') as f:
       ftext = f.read().split() #the file has only space-separated numbers
       ftext = [float(n) for n in ftext]
       numbers.append(  np.array( ftext ) )

numbers = np.vstack(numbers)

sum_over_first_cells = np.sum( numbers[:,0] )