Initialize a numpy array to save other arrays in it?

Question

My goal is it to save 2 different arrays in a new numpy array.

I tried a few things and this worked for me:

state_vek = np.array([array1, array2])

array1 and array2 are have different dimensions.

But as i am working with classes i would need to initialize state_vek beforehand.

Then I tried this:

state_vek = np.zeros(2)
state_vek[0] = array1
state_vek[1] = array2

Which resulted in following error:

ValueError: setting an array element with a sequence.

So my question is, how am i supposed to initialize my state_vek so i can use this line state_vek[0] = array1?

What, exactly is the result you are looking for? If you want to be able to store any arbitrary array, just use a list. — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Dec 26, 2020 at 14:02
In the first case what's the shape of the two arrays and the result? What's their dtypes? — hpaulj
– hpaulj, Commented Dec 26, 2020 at 15:19
@juanpa.arrivillaga My goal is it to use the array or list as input for a neural network. The first array is a (4,160,120,1) array which gets passed to an convolutional neural network as input The output of this CNN gets flattened into an long array and then i wanted to append array2 to that flattened array. The storing of the states is also done via numpy arrays that why i would like an solution with numpy array. Im aware of the existance of lists — Qilos
– Qilos, Commented Dec 26, 2020 at 16:06
An object dtype array is no better, and often worse, than a list with the same components. So far you problem description is incomplete. — hpaulj
– hpaulj, Commented Dec 26, 2020 at 17:28

Adit Goyal · Accepted Answer · 2020-12-26 13:56:32Z

1

If you know the dimensions of array1 and array2 beforehand, you can do something like this:

import numpy as np

arr1 = np.array([1,2,3])
arr2 = np.array([4,5,6])
b = np.zeros((2,3)) #np.zeros(shape, dtype = None, order = 'C')

b[0] = arr1
b[1] = arr2
print(b)

Output:

[[1. 2. 3.]
 [4. 5. 6.]]

answered Dec 26, 2020 at 13:56

Adit Goyal

364 bronze badges

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

2 Comments

Qilos Over a year ago

Hello, thanks for your answer. How would you do that if array1 had the shape of (4,160,120,1) and array2 had the shape of (1,)?

Adit Goyal Over a year ago

Just use python lists to store, and convert in numpy arrays using asarray() function when you want to perform any operations.

Collectives™ on Stack Overflow

Initialize a numpy array to save other arrays in it?

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related