Python – 字符串列表中的特定字符频率

给定字符串列表，提取整个字符串列表中特定字符的频率。

Input : test_list = [“geeksforgeeks is best for geeks”], chr_list = [‘e’, ‘b’, ‘g’, ‘f’]
Output : {‘g’: 3, ‘e’: 7, ‘b’: 1, ‘f’ : 1}
Explanation : Frequency of certain characters extracted.

Input : test_list = [“geeksforgeeks], chr_list = [‘e’, ‘g’]
Output : {‘g’: 2, ‘e’: 4}
Explanation : Frequency of certain characters extracted.

方法 #1：使用 join() + Counter()

在此，我们连接所有字符串，然后 Counter() 执行获取所有频率的任务。最后一步是使用字典理解从字典中的列表中仅获取特定字符。

Python3

# Python3 code to demonstrate working of 
# Specific Characters Frequency in String List
# Using join() + Counter()
from collections import Counter
  
# initializing lists
test_list = ["geeksforgeeks is best for geeks"]
  
# printing original list
print("The original list : " + str(test_list))
  
# char list 
chr_list = ['e', 'b', 'g']
  
# dict comprehension to retrieve on certain Frequencies
res = {key:val for key, val in dict(Counter("".join(test_list))).items() if key in chr_list}
      
# printing result 
print("Specific Characters Frequencies : " + str(res))

输出

The original list : ['geeksforgeeks is best for geeks']
Specific Characters Frequencies : {'g': 3, 'e': 7, 'b': 1}

方法 #2：使用 chain.from_iterable() + Counter() + 字典理解

在此，连接任务是使用 chain.from_iterable() 而不是 join() 完成的。其余所有任务都按上述方法完成。

Python3

# Python3 code to demonstrate working of 
# Specific Characters Frequency in String List
# Using chain.from_iterable() + Counter() + dictionary comprehension
from collections import Counter
from itertools import chain
  
# initializing lists
test_list = ["geeksforgeeks is best for geeks"]
  
# printing original list
print("The original list : " + str(test_list))
  
# char list 
chr_list = ['e', 'b', 'g']
  
# dict comprehension to retrieve on certain Frequencies
# from_iterable to flatten / join
res = {key:val for key, val in dict(Counter(chain.from_iterable(test_list))).items() if key in chr_list}
      
# printing result 
print("Specific Characters Frequencies : " + str(res))

输出

The original list : ['geeksforgeeks is best for geeks']
Specific Characters Frequencies : {'g': 3, 'e': 7, 'b': 1}