CODEWITHSUNDEEP
pythonnumpymatrix
Aggelos Vassilakos
Aggelos Vassilakos

Reputation: 13

How can I produce matrixes automatically in Python?

I have

x = np.linspace(0, 1, 6)
y = np.linspace(0, 1, 9)

How can I have a matrix 7x10 from (x,y) but each row becomes from the previous one by adding 1? For example, the first row is

0,1,2,3,4,5,6

the second row

1,2,3,4,5,6,7

and so on

Upvotes: 1

Views: 49

Answers (1)

perl
perl

Reputation: 9941

With broadcasting in numpy:

x = np.arange(7)
y = np.arange(10)

x[np.newaxis, :] + y[:, np.newaxis]

Output:

array([[ 0,  1,  2,  3,  4,  5,  6],
       [ 1,  2,  3,  4,  5,  6,  7],
       [ 2,  3,  4,  5,  6,  7,  8],
       [ 3,  4,  5,  6,  7,  8,  9],
       [ 4,  5,  6,  7,  8,  9, 10],
       [ 5,  6,  7,  8,  9, 10, 11],
       [ 6,  7,  8,  9, 10, 11, 12],
       [ 7,  8,  9, 10, 11, 12, 13],
       [ 8,  9, 10, 11, 12, 13, 14],
       [ 9, 10, 11, 12, 13, 14, 15]])

Or the same thing with np.reshape:

x.reshape(1, -1) + y.reshape(-1, 1)

And here's possibly a little more readable, but significantly less computationally efficient:

m = np.empty((10, 7))
for i in range(10):
    for j in range(7):
        m[i, j] = i + j

Upvotes: 3

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