Python SymPy Permutation.descents()方法

Permutation.descents() : descents()是一个Sympy Python库函数，用于返回permutation中descents的位置。降序是指**a[i] > a[i+1] **的元素。

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

返回：在排列组合中的下降位置

代码 #1 : descents() 示例

# 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())

输出 :

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

代码#2：descents()示例–二维排布

# 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())

输出 :

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