# Python | SymPy Permutation.index() method

• Last Updated : 27 Aug, 2019

Permutation.index() : index() is a sympy Python library function that returns the index value of the permutation in argument.

Index of a permutation = Sum of all subscripts j such that permutation[j] is greater than permutation[j+1].

Syntax :
sympy.combinatorics.permutations.Permutation.index()

Return :
index value of the permutation

Code #1 : index() Example

 `# Python code explaining``# SymPy.Permutation.index()`` ` `# importing SymPy libraries``from` `sympy.combinatorics.partitions ``import` `Partition``from` `sympy.combinatorics.permutations ``import` `Permutation`` ` `# Using from sympy.combinatorics.permutations.Permutation.index() method `` ` `# creating Permutation``a ``=` `Permutation([[``2``, ``0``], [``3``, ``1``]])`` ` `b ``=` `Permutation([``1``, ``3``, ``5``, ``4``, ``2``, ``0``])`` ` ` ` `print` `(``"Permutation a - index form : "``, a.index())``print` `(``"Permutation b - index form : "``, b.index())`

Output :

Permutation a – index form : 1
Permutation b – index form : 9

Code #2 : index() Example – 2D Permutation

 `# Python code explaining``# SymPy.Permutation.index()`` ` `# importing SymPy libraries``from` `sympy.combinatorics.partitions ``import` `Partition``from` `sympy.combinatorics.permutations ``import` `Permutation`` ` `# Using from sympy.combinatorics.permutations.Permutation.index() method `` ` `# creating Permutation``a ``=` `Permutation([[``2``, ``4``, ``0``], ``                 ``[``3``, ``1``, ``2``],``                 ``[``1``, ``5``, ``6``]])`` ` ` ` `print` `(``"Permutation a - index form : "``, a.index())`

Output :

Permutation a – index form : 8

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