Python中的SymPy Permutation.inversions()

Permutation.inversions() : inversions()是一个sympy Python库函数，用于返回参数中permutation的反转值的数量。
反转向量包括这些元素，其值表示排列组合中<它并位于其右侧的元素的数量。

返回：参数中的排列组合的倒置值数量

代码 #1 : inversions() 示例

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

输出 :

Permutation a – inversions form : 4
Permutation b – inversions form : 9

代码 #2 : inversions() 例子 – 二维互换

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

输出 :