Python | SymPy placement.index()方法

原文:https://www.geesforgeks.org/python-sympy-排列-索引-方法/

arrange.index():index()是一个 sympy Python 库函数，返回参数中排列的索引值。

置换的索引= 所有下标 j 的和，使得置换[j]大于置换[j+1]。

语法: sympy.combinations .排列.置换. index()

返回: 排列的索引值

代码#1:索引()示例

# 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())

输出:

排列 a–索引形式:1 排列 b–索引形式:9

代码#2:索引()示例–2D 置换

# 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())

输出:

排列 a–索引形式:8

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