CODEWITHSUNDEEP
pythonlist
Fred
Fred

Reputation: 60

List items can't get multiplied

I have a basic question:
There are two lists named a1 and b1. If I print out one item of each list, it would be a float number, but when I use a1[i]*b1[i] in a loop, it gives an error: 

TypeError: can't multiply sequence by non-int of type 'float'

Why is that?

Upvotes: 1

Views: 136

Answers (2)

daedalus12
daedalus12

Reputation: 384

Think @Gille probably got your error.

If all you want to do in your loop is multiply entries together, the fast way would be to use numpy arrays:

import numpy as np
result = np.multiply(a1,b1)

Cast back to a list if necessary:

result = list(result)

Upvotes: 1

Gille
Gille

Reputation: 5773

Either a1 or b1 is not list of floats but a list of lists of floats.

a1=[1.234, 1.234];
a2=[1.234, 1.234];
>>> a1[0]*a2[0]
1.522756

a3=[[1.234], [1.234]];

>>> a1[0]*a3[0]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: can't multiply sequence by non-int of type 'float'

Upvotes: 3

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