How can I convert a 3D list into a 2D list in python?

Question

This is the code that I have:

[[[3], [4]], [[5], [6]], [[7], [8]]]

How can I change it into:

[[3], [4], [5], [6], [7], [8]]

?

Answer 1

You want to flatten a single level of the input list, try this solution using a list comprehension:

lst = [[[3], [4]], [[5], [6]], [[7], [8]]]
[e for sl in lst for e in sl]
=> [[3], [4], [5], [6], [7], [8]]

Answer 2

try this:

import numpy as np
a = np.array([[[3],[4]],[[5],[6]],[[7],[8]]])
b = a.reshape(6,1)

Answer 3

A uncompressed or long way:

l3d = [[[3], [4]], [[5], [6]], [[7], [8]]]
l2d = []
for e1 in l3d:
   for e2 in e1:
      l2d.append(e2)

Answer 4

# Provided list
lst = [[[3], [4]], [[5], [6]], [[7], [8]]]

# To do this we are going to import chain from itertools
from itertools import chain

final = list(chain(*lst))

print(final)  # Output: [[3], [4], [5], [6], [7], [8]]