Make a for loop assign different variables?

[valestrom]

print ("The scope of this program is to multiply two matrices together\
and print the result")


while True:
    matrix1_rows = input("How many rows does matrix one have? ")
    matrix1_columns = input("How many columns does matrix one have? ")

    print ("Matrix one is a", matrix1_rows, "x", matrix1_columns, "matrix")
    print()

    matrix2_rows = input("How many rows does matrix two have? ")
    matrix2_columns = input("How many columns does matrix one have? ")

    print ("Matrix two is a", matrix2_rows, "x", matrix2_columns, "matrix")

    if(matrix1_columns != matrix2_rows):
        print("\nSorry, cannot multiply these two matrices, must be (mxn)*(nxp)")


    else:
        break


print("----------------------------------------------------------")
print("\nThe system will now take values for matrix one, one row at a time")
print("Enter the values of the first row, click enter then the second row, and so on")

for i in range (0, int(matrix1_rows)):

        if (i == 0):
            matrix1_row1_set = input("Please enter the values for the row\n")

I want to be able to have the user enter the number of rows that the matrix has and then ask for each rows value (Like user entering "1 0 5 9 5") and assigning that to the variable matrix1_row1_set then getting another row and assigning it to a variable like matrix1_row2_set

What would be the most efficient way to do this?

[Gribouillis]

The most efficient way is to append the rows one at a time to a list:

...
matrix1_rows = input(...)
matrix1_rows = int(matrix1_rows)
...
matrix1 = []

for i in range(matrix1_rows):
    ... input ...
    row = ...
    matrix1.append(row)

after this loop, the rows will be matrix1[0], matrix1[1],... up to matrix1[1matrix1_rows - 1].

[valestrom]

That sounds so smart, I talked to my prof and he suggested the same kind of thing. Just without hard code in the example. Thanks!

[David W]

You might like to also try data entry something like this:

# takeInMatrix.py #


def takeInRow( numCols ):
    data = input( "Enter "+str(numCols)+" numbers separated by a space: ")
    items = data.split()

    good = True
    cols = []
    for item in items:
        try:
            num = float(item)
            cols.append( num )
        except:
            print( "There was some invalid data ... " )
            good = False
    return good, cols




def takeInMatrix( rows, cols ):
    matrix = []
    i = 0
    while i < rows:
        good, row = takeInRow( cols )
        if good:
            if len(row) == cols:
                matrix.append( row )
                i += 1
            else:
                print( "\nMust be", cols, "numbers entered ..\n" )
        else:
            print( "Try again ... " )

    return matrix



mat = takeInMatrix( 3, 5 )

for row in mat:
    print( row )