How to insert an array of floats into another array at specific index in Python

Question

I have a numpy array as follows:

matrix = array([[0.],
       [1.],
       [2.],
       [3.],
       [4.]])

I have another array:

x = [0.05385944 0.05419472 0.05453447 0.05487901]

I would like to insert the second array into the first index of the first array such like:

matrix = array([[0. 0.05385944 0.05419472 0.05453447 0.05487901],
       [1.],
       [2.],
       [3.],
       [4.]])

I have tried

matrix = np.insert(matrix, 1, x),

but this is creating an array as such:

array([ 0. 0.05385944, 0.05419472,  0.05453447,  0.05487901, 1., 2., 3., 4.])

Alain T. · Accepted Answer · 2020-12-04 14:27:10Z

2

Numpy does not support variable dimensions. So it cannot have a row that has more elements than others.

Regular Python lists can do it though:

matrix = [[0.],
       [1.],
       [2.],
       [3.],
       [4.]]

x = [0.05385944, 0.05419472, 0.05453447, 0.05487901]

matrix[0].extend(x)

for row in matrix:print(row)

[0.0, 0.05385944, 0.05419472, 0.05453447, 0.05487901]
[1.0]
[2.0]
[3.0]
[4.0]

answered Dec 4, 2020 at 14:27

Alain T.

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2 Comments

Dragmoogle Over a year ago

How would I create the original matrix without numpy? I am currently using d = range(5) matrix = np.column_stack([d])

Alain T. Over a year ago

matrix = [ [float(i)] for i in range(5) ]

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