Multiplying elements of one column with all elements from another data set

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I have some data frame 'A' like this (I think this is pandas series):

1
2
3
4

and another data set 'B' looks like this (this is I think numpy.ndarray):

[5 4 3 2 1]

I am trying to multiply first element from 'A' with all elements from 'B', second element from 'A' with all elements from 'B' ..... so at the end I will have something like this:

5 4 3 2 1
10 8 6 4 2
15 12 9 6 3
20 16 12 8 4

I would like to avoid using any loop here if this is possible.

Any suggestion or advices .... Thanks.

pandas numpy python
1 Answers

Use numpy broadcasting:

s = pd.Series(range(1,5))

a = np.array([5, 4, 3, 2, 1])

out = s.to_numpy()[:, None] * a
print (out)
[[ 5  4  3  2  1]
 [10  8  6  4  2]
 [15 12  9  6  3]
 [20 16 12  8  4]]

If need DataFrame:

df = pd.DataFrame(out)
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