SymPy | Python中的 Subset.prev_lexicographic()

Subset.prev_lexicographic() ：prev_lexicographic()是一个 sympy Python库函数，它返回前一个按字典顺序排列的子集。

Syntax :
sympy.combinatorics.subset.Subset.prev_lexicographic()

Return :
the previous Gray code ordered subset.

代码 #1：prev_lexicographic() 示例

# Python code explaining
# SymPy.Subset.prev_lexicographic()
  
# importing SymPy libraries
from sympy.combinatorics import Permutation, Cycle
from sympy.combinatorics.subsets import Subset
  
# Using from 
# sympy.combinatorics.subset.Subsets.prev_lexicographic()
  
# Creating Subset
a = Subset(['c', 'd'], ['geek', 'for', 'c', 'd'])
  
# prev_lexicographic value
print ("Subset a prev_lexicographic : ", a.prev_lexicographic().subset)

输出 ：

Subset a prev_lexicographic : [‘c’]

代码 #2：prev_lexicographic() 示例

# Python code explaining
# SymPy.Subset.prev_lexicographic()
  
# importing SymPy libraries
from sympy.combinatorics import Permutation, Cycle
from sympy.combinatorics.subsets import Subset
  
# Using from 
# sympy.combinatorics.subset.Subsets.prev_lexicographic()
  
# Creating Subset
a = Subset([2, 3, 4], [1, 2, 3, 4, 5])
  
# prev_lexicographic value
print ("Subset a prev_lexicographic : ", a.prev_lexicographic().subset)

输出 ：

Subset a prev_lexicographic : [2, 3]