splitting numeric list based on condition

[michalmonday]

I hope this clarifies what's going on in there, but the best way is to check every part of the expression yourself by printing parts of it (or also modifying/playing with them) using interpreter

import numpy as np

# np.array allows to use "array-oriented" math operations
# For example using:
# num_arr == 5

# Doing that to a list will return single "True" or "False"
# Doing that to np.array will return another array containing "True" or "False"
# corresponding to each value in the array

# [5,10] == 5 evaluates to "False"
# np.array([5,10]) == 5 evaluates to "array([True, False])"

# So if you want to easily apply some operation (possibly using some numpy
# functions) to an array then using np.array() makes it convenient.

num_arr = np.array([0,1,2,3,4,5,1,2,3,4,5,2,3,4,5])

indices_where_5_is_found = np.where(num_arr[:-1] == 5)[0] + 1

print('Array:', num_arr, '\n')

print('At which indices 5 was found:\n', indices_where_5_is_found, '\n')

# Notice that if we didn't use [:-1] then the index of the last 5
# would also be included (resulting in additional empty sub-list),
# [:-1] removes the last item from the array.

print("At which indices 5 would be found if [:-1] wasn't used:\n", np.where(num_arr == 5)[0] + 1, '\n')
print("Result if [:-1] wasn't used:\n", np.split(num_arr, np.where(num_arr == 5)[0] + 1), '\n')


# If +1 wasn't used then 5 would be included as the first item of each
# sub-list

# np.array([1,2]) + 1 increases each item of the array by 1, resulting in:
# array([2,3])

print("Indices if +1 wasn't used:\n", np.where(num_arr[:-1] == 5)[0], '\n')
print("Result if +1 wasn't used:\n", np.split(num_arr, np.where(num_arr[:-1] == 5)[0]), '\n')

arrays = np.split(num_arr, indices_where_5_is_found)
print('Final result:\n', arrays, '\n')

Output:
Array: [0 1 2 3 4 5 1 2 3 4 5 2 3 4 5] 

At which indices 5 was found:
 [ 6 11] 

At which indices 5 would be found if [:-1] wasn't used:
 [ 6 11 15] 

Result if [:-1] wasn't used:
 [array([0, 1, 2, 3, 4, 5]), array([1, 2, 3, 4, 5]), array([2, 3, 4, 5]), array([], dtype=int32)] 

Indices if +1 wasn't used:
 [ 5 10] 

Result if +1 wasn't used:
 [array([0, 1, 2, 3, 4]), array([5, 1, 2, 3, 4]), array([5, 2, 3, 4, 5])] 

Final result:
 [array([0, 1, 2, 3, 4, 5]), array([1, 2, 3, 4, 5]), array([2, 3, 4, 5])]