# Python | SymPy Permutation.descents() method

Permutation.descents() : descents() is a sympy Python library function that returns the position of descents in the permutation. Descents are the elements where a[i] > a[i+1]

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

Return : position of descents in the permutation

Code #1 : descents() Example

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

Output :

Permutation a – descents form : [1]
Permutation b – descents form : [2, 3, 4]

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

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

Output :

Permutation a – descents form : [0, 3, 5]

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