4.7. index_natsorted()

natsort.index_natsorted(seq, key=None, reverse=False, alg=0, **_kwargs)

Determine the list of the indexes used to sort the input sequence.

Sorts a sequence naturally, but returns a list of sorted the indexes and not the sorted list itself. This list of indexes can be used to sort multiple lists by the sorted order of the given sequence.

Parameters:
  • seq (iterable) – The input to sort.
  • key (callable, optional) – A key used to determine how to sort each element of the sequence. It is not applied recursively. It should accept a single argument and return a single value.
  • reverse ({True, False}, optional) – Return the list in reversed sorted order. The default is False.
  • alg (ns enum, optional) – This option is used to control which algorithm natsort uses when sorting. For details into these options, please see the ns class documentation. The default is ns.INT.
Returns:

out – The ordered indexes of the input.
Return type:

tuple

See also

natsorted(), order_by_index()

Examples

Use index_natsorted if you want to sort multiple lists by the sorted order of one list:

>>> a = ['num3', 'num5', 'num2']
>>> b = ['foo', 'bar', 'baz']
>>> index = index_natsorted(a)
>>> index
[2, 0, 1]
>>> # Sort both lists by the sort order of a
>>> order_by_index(a, index)
['num2', 'num3', 'num5']
>>> order_by_index(b, index)
['baz', 'foo', 'bar']