Python| sympy.nP() 方法

借助sympy.nP()方法，我们可以计算 SymPy 中给定长度的排列数。

Syntax: nP(items, k)

Parameter:
items – An integer, a list or a string upon which permutation is to be calculated.
k – An integer specifying the length of the permutation.

Returns: Returns the number of permutation of a given length.

示例 #1：

# import sympy 
from sympy import * 
  
items = "abca"
k = 3
print("Value of k = {} and the items are = {}".format(k, items))
   
# Use sympy.nP() method 
permutations = nP(items, k)  
      
print("Permutation : {}".format(permutations))  

输出：

Value of k = 3 and the items are = abca
Permutation : 12

示例 #2：

# import sympy 
from sympy import * 
  
items = [2, 1, 3, 5, 4]
k = 3
print("Value of k = {} and the items are = {}".format(k, items))
   
# Use sympy.nP() method 
permutations = nP(items, k)  
      
print("Permutation : {}".format(permutations))  

输出：

Value of k = 3 and the items are = [2, 1, 3, 5, 4]
Permutation : 60