How to do this in Python?

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The** argsort()** function of Numpy can be used. You can sort the indices of sublists by using the length of sublists as an argument of the **argsort()** function. You can then use the sorted indices to sort the list of sublists.

Here is an example:

Let's generate a list of sublists with different lengths:

>>> import numpy as np

>>> import random

>>> a=[[random.randint(10,45) for _ in range(4)]]

>>> a.append([random.randint(10,90) for _ in range(8)])

>>> a.append([random.randint(10,90) for _ in range(5)])

>>> a.append([random.randint(10,90) for _ in range(9)])

>>> a.append([random.randint(10,90) for _ in range(3)])

>>> a

[[14, 14, 11, 19], [85, 52], [82, 80, 45, 33, 73, 34, 84, 37], [86, 77, 67, 25, 79], [66, 45, 58, 28, 53, 51, 48, 34, 39], [83, 15, 29]]

Now, create a list of the length of sublists and use the **argsort()** function to sort the indices by length.

>>> counts = [len(v) for v in a]

>>> counts

[4, 2, 8, 5, 9, 3]

>>> i=np.argsort(counts)

>>> i

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

Now, you can use the sorted indices to sort the list of lists.

>>> list(np.array(a)[i])

[[85, 52], [83, 15, 29], [14, 14, 11, 19], [86, 77, 67, 25, 79], [82, 80, 45, 33, 73, 34, 84, 37], [66, 45, 58, 28, 53, 51, 48, 34, 39]]