Add element after each element in numpy array python

Question

I am just starting off with numpy and am trying to create a function that takes in an array (x), converts this into a np.array, and returns a numpy array with 0,0,0,0 added after each element.

It should look like so:

input array: [4,5,6]

output: [4,0,0,0,0,5,0,0,0,0,6,0,0,0,0]

I have tried the following:

   import numpy as np
   x = np.asarray([4,5,6])
   y = np.array([])
   for index, value in enumerate(x):
        y = np.insert(x, index+1, [0,0,0,0])
        print(y)

which returns:

[4 0 0 0 0 5 6]
[4 5 0 0 0 0 6]
[4 5 6 0 0 0 0]

So basically I need to combine the output into one single numpy array rather than three lists.

Would anybody know how to solve this?

Many thanks!

rambi · Accepted Answer · 2020-02-22 15:46:46Z

3

Use the numpy .zeros function !

import numpy as np

inputArray = [4,5,6]

newArray = np.zeros(5*len(inputArray),dtype=int)
newArray[::5] = inputArray

In fact, you 'force' all the values with indexes 0,5 and 10 to become 4,5 and 6.

so _____[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

becomes [4 0 0 0 0 5 0 0 0 0 6 0 0 0 0]

>>> newArray
array([4, 0, 0, 0, 0, 5, 0, 0, 0, 0, 6, 0, 0, 0 ,0])

edited Feb 22, 2020 at 15:46

answered Feb 22, 2020 at 15:01

rambi

1,2992 gold badges12 silver badges30 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

DSLBG13 Over a year ago

So just to make sure I understood the code correctly:So just to make sure I understood the code correctly:

numberOfZeros = 4  inputArray = [4,5,6]  newArray = np.zeros((numberOfZeros+1)*len(inputArray),dtype=int) ##creates newArray with space for the inputArray + zeroes newArray[::(numberOfZeros+1)] = inputArray ## plugs in the input values, but could you explain this to me?

Thanks!

Aayman Khalid · Accepted Answer · 2020-02-22 15:01:57Z

3

I haven't used numpy to solve this problem,but this code seems to return your required output:

a = [4,5,6]
b = [0,0,0,0]
c = []
for x in a:
   c = c + [x] + b
print(c)

I hope this helps!

answered Feb 22, 2020 at 15:01

Aayman Khalid

4683 gold badges12 silver badges26 bronze badges

1 Comment

DSLBG13 Over a year ago

That seems so simple now! Thank you!

Collectives™ on Stack Overflow

Add element after each element in numpy array python

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related