Inserting elements at specific positions in an array in a list in Python

Question

I have a list A containing a numpy array. I want to insert element C1 at specific positions in A according to J. But I am getting an error. I have included the expected output.

import numpy as np
J=[[4, 7, 10]]
C1=[0]

A=[np.array([10.                 ,  0.6382821834929432 ,  0.5928417218382795 ,
        0.5542698411479658 ,  0.6677634679746701 ,  0.8578897621707481 ,
        0.6544597670890333 ,  0.32706383813570833,  0.8966468940380192 ])]


A=np.insert(A[0],J,[C1],axis=1)

The error is

in <module>
    A=np.insert(A[0],J,[C1],axis=0)

  File "<__array_function__ internals>", line 5, in insert

  File "C:UsersUSERanaconda3libsite-packagesnumpylibfunction_base.py", line 4626, in insert
    raise ValueError(

ValueError: index array argument obj to insert must be one dimensional or scalar

The expected output is

A=[np.array([10.                 ,  0.6382821834929432 ,  0.5928417218382795 ,
         0.5542698411479658 ,  0, 0.6677634679746701 ,  0.8578897621707481 ,
         0, 0.6544597670890333 ,  0.32706383813570833,  0, 0.8966468940380192 ])]

Asked By: Klimt865

||

Source

Answer 1

It works like this:

import numpy as np

# need to take the indices based on the array before anything is inserted
J = [[4, 6, 8]]
C1 = [0]

A = [np.array([10.                 ,  0.6382821834929432 ,  0.5928417218382795 ,
        0.5542698411479658 ,  0.6677634679746701 ,  0.8578897621707481 ,
        0.6544597670890333 ,  0.32706383813570833,  0.8966468940380192 ])]

A = np.insert(A[0], J[0], C1[0])

Output A:

array([10.        ,  0.63828218,  0.59284172,  0.55426984,  0.        ,
        0.66776347,  0.85788976,  0.        ,  0.65445977,  0.32706384,
        0.        ,  0.89664689])

Notice that A is not a list with a np.array anymore, it is just the np.array now.

EDIT
insert one at a time with given indices.

J = [[4, 7, 10]]
C1 = [0]

A = [np.array([10.                 ,  0.6382821834929432 ,  0.5928417218382795 ,
        0.5542698411479658 ,  0.6677634679746701 ,  0.8578897621707481 ,
        0.6544597670890333 ,  0.32706383813570833,  0.8966468940380192 ])]

for elem in J[0]:
    A = [np.insert(A[0], elem, C1[0])]

Answered By: Rabinzel

Inserting elements at specific positions in an array in a list in Python

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