Read From A Text File. - Python

My question: For example, my text file is call 'feed.txt'. and for inside, it likes that: 2 # two means 'there are two matrix in this file' 3 # three means 'the below one is a 3*3

Solution 1:

Okay, gonna take you through this step by step. If 'file' is your file name, try:

matrices = []                    # The list you'll be keeping your matrices inwithopen('file') as f:
    num_matrices = int(f.readline())
    for mat_index inrange(num_matrices):
        temp_matrix = []         # The list you'll keep the rows of your matrix in
        num_rows = int(f.readline())
        for row_index inrange(num_rows):
            line = f.readline()
            # Split the line on whitespace, turn each element into an integer
            row = [int(x) for x in line.split()]
            temp_matrix.append(row)
        matrices.append(temp_matrix)

Then each of your matrices will be stored in an index of matrices. You can iterate through these as you like:

for my_matrix in matrices:
    # Do something hereprint my_matrix

For the second part on summing the rows, you have two options if you want this to work correctly. Either use i to index into a row of your list:

for i inrange(len(my_matrix):
    total = sum(my_matrix[i])
    print(total)

Or use the more Pythonic way and iterate directly over your sub-lists:

forrowin my_matrix:
    total =sum(row)
    print(total)

If you want to save each of these individual results for later use, you'll have to make a list for your results. Try:

>>>sumz = []>>>for row in my_matrix:
    sumz.append(sum(row))

>>>sumz
[15, 15, 15]