Python| SymPy Permutation.from_sequence() 方法

Permutation.from_sequence() ：from_sequence()是一个 sympy Python库函数，它返回从“i”的排序元素中获取“i”所需的排列。如果需要任何自定义字符串，也可以将“键”作为参数传递。

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

Return :
returns the permutation which is required to
obtain ‘i’ from the sorted elements of ‘i’

代码 #1：from_sequence() 示例

# Python code explaining
# SymPy.from_sequence()
  
# importing SymPy libraries
from sympy.combinatorics.partitions import Partition
from sympy.combinatorics.permutations import Permutation
  
# Using from 
# sympy.combinatorics.permutations.Permutation.from_sequence() method 
  
# creating vectors
a = [1, 0, 0, 0]
  
b = [6, 5, 4, 3, 0, 0 ]
  
# inversion forms
print ("vector a - from_sequence form : \n", Permutation.from_sequence(a))
print ("vector b - from_sequence form : \n", Permutation.from_sequence(b))

输出 ：

vector a – from_sequence form :
Permutation([3, 0, 1, 2])

vector b – from_sequence form :
Permutation([5, 4, 3, 2, 0, 1])

代码 #2 : from_sequence() 示例——使用字符串和键

# Python code explaining
# SymPy.from_sequence()
  
# importing SymPy libraries
from sympy.combinatorics.partitions import Partition
from sympy.combinatorics.permutations import Permutation
  
# Using from sympy.combinatorics.permutations.Permutation.from_sequence() method 
  
# creating vector
a = [2, 3, 1, 0]
  
# inverted vector of a
print ("vector a - from_sequence form : ", 
       Permutation.from_sequence(a))
  
# length = 5, so permutation as per that.
print ("\nstring - from_sequence form : ", 
       Permutation.from_sequence('GEEKS'))
  
  
# length = 5, so permutation as per that.
# defining a key
print ("\nstring - from_sequence form : ", 
       Permutation.from_sequence('GEEKS', key = lambda x: x.lower()))

输出 ：

vector a – from_sequence form : Permutation([2, 3, 1, 0])

string – from_sequence form : Permutation([2, 0, 1, 3, 4])

string – from_sequence form : Permutation([2, 0, 1, 3, 4])