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Transposing a Matrix WITHOUT numpy - TreasureDragon - Mar-01-2019
So our assignment is to ask for user input for two matrices and then multiply them and show the result then switch the result to a transpose. Since I did it in 1D instead of 2D, I have to transpose the original A and B rather than C. So how can I do this? This is what I have so far and all of this works as intended. Just need help with the transposing part:
Ar, Ac = input("Enter matrix A rows and columns: ").split()
Br, Bc = input("Enter matrix B rows and columns: ").split()
A = input("Enter matrix A: ").split()
B = input("Enter matrix B: ").split()
intAr, intAc = int(Ar), int(Ac)
intBr, intBc = int(Br), int(Bc)
AMatrix = list()
BMatrix = list()
CMatrix = list()
if Ac == Br:
print(f"\nMatrix A:")
for x in range(intAr):
AList = list()
for y in range(intAc):
AList.append(int(A[y + intAc*x]))
print(str(A[y+intAc*x])," ", end = '')
AMatrix.append(AList)
print()
print(f"\nMatrix B:")
for x in range(intBr):
BList = list()
for y in range(intBc):
BList.append(int(B[y + intBc*x]))
print(str(B[y+intBc*x])," ", end = '')
BMatrix.append(BList)
print()
print(f"\nMatrix C:")
for x in range(intAr):
for y in range(intBc):
C = 0
for z in range(intBr):
C += (AMatrix[x][z] * BMatrix[z][y])
CMatrix.append(C)
print(C, ' ', end ='')
print()
print(f"\nTranspose matrix T:")
else:
print(f"\nCannot be multiplied. Please make sure the number of columns of A and rows of B are the same.")
RE: Transposing a Matrix WITHOUT numpy - ichabod801 - Mar-01-2019
It's incredibly simple to transpose a 2D matrix in Python:
transposed = zip(*matrix)It's so simple, that if you are working in 1D, I would suggest converting to 2D to do the transposition.
RE: Transposing a Matrix WITHOUT numpy - TreasureDragon - Mar-02-2019
(Mar-01-2019, 10:46 PM)ichabod801 Wrote: It's incredibly simple to transpose a 2D matrix in Python:
transposed = zip(*matrix)It's so simple, that if you are working in 1D, I would suggest converting to 2D to do the transposition.
How can I convert the C Matrix into a 2D Matrix though? Sorry, this is my first semester ever in compsci so I am so lost right now.
RE: Transposing a Matrix WITHOUT numpy - ichabod801 - Mar-02-2019
Well, looking at your code, you are actually working in 2D. Your matrices are stored as a list of lists. So you can just use the code I showed you. Note that it will give you a generator, not a list, but you can fix that by doing
transposed = list(zip(*matrix))The reason it works is that zip takes any number of lists as parameters. It then returns a list of the first item in each list, a list of the second item in each list, a list of the third item in each list, and so on. The star (*) notation converts a sequence (like a list) into a series of parameters.
RE: Transposing a Matrix WITHOUT numpy - TreasureDragon - Mar-02-2019
(Mar-02-2019, 06:55 PM)ichabod801 Wrote: Well, looking at your code, you are actually working in 2D. Your matrices are stored as a list of lists. So you can just use the code I showed you. Note that it will give you a generator, not a list, but you can fix that by doingtransposed = list(zip(*matrix))
The reason it works is that zip takes any number of lists as parameters. It then returns a list of the first item in each list, a list of the second item in each list, a list of the third item in each list, and so on. The star (*) notation converts a sequence (like a list) into a series of parameters.
Oh. So just simply use the code? But it's a library function isn't it... We aren't allowed to use those for now :(
And the code didn't work...
RE: Transposing a Matrix WITHOUT numpy - ichabod801 - Mar-02-2019
It's a built-in function, just like list, int, range, and input.
You could write a set of loops to do what I described: get a list of the first item in each list, a list of the second item in each list, a list of the third item in each list, and so on. But you would have to loop through the indexes of the list and the sub-lists, which wouldn't be very Pythonic.