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Python | Count occurrence of all elements of list in a tuple

  • Last Updated : 15 Mar, 2019

Given a tuple and a list as input, write a Python program to count the occurrences of all items of the list in the tuple.

Examples:

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Input : tuple = ('a', 'a', 'c', 'b', 'd')
        list = ['a', 'b']
Output : 3 

Input : tuple = (1, 2, 3, 1, 4, 6, 7, 1, 4)
        list = [1, 4, 7]
Output : 6

 
Approach #1 : Naive Approach



The first approach is the naive approach. Use a for loop and traverse through the given list and count the occurrence of each item of tuple in a list. Finally, return the count.




# Python3 Program to count occurrence 
# of all elements of list in a tuple
from collections import Counter
  
def countOccurrence(tup, lst):
    count = 0
    for item in tup:
        if item in lst:
            count+= 1
      
    return count 
      
# Driver Code
tup = ('a', 'a', 'c', 'b', 'd')
lst = ['a', 'b']
print(countOccurrence(tup, lst))
Output:
3

 
Approach #2 : Using Counter
From Python Collections module, import counter to solve the given problem. A Counter is a container that keeps track of how many times equivalent values are added. Having saved the resultant in ‘counts’, we use a for loop and count how many times each item in list occurs in ‘counts’ and sum it to give the final output.




# Python3 Program to count occurrence 
# of all elements of list in a tuple
from collections import Counter
  
def countOccurrence(tup, lst):
    counts = Counter(tup)
    return sum(counts[i] for i in lst)
      
# Driver Code
tup = ('a', 'a', 'c', 'b', 'd')
lst = ['a', 'b']
print(countOccurrence(tup, lst))
Output:
3

 
Approach #3 : Using Set
Another method of solving the given problem is using set data structure. Simply convert the given list into a set, which removes all duplicates. And now, for each item of list, count its occurrence in tuple and sum them.




# Python3 Program to count occurrence 
# of all elements of list in a tuple
  
def countOccurrence(tup, lst):
    lst = set(lst)
    return sum(1 for x in tup if x in lst)
      
# Driver Code
tup = ('a', 'a', 'c', 'b', 'd')
lst = ['a', 'b']
print(countOccurrence(tup, lst))
Output:
3

 
Approach #4 : Using Python dictionary
Get each item of tuple and its frequency as key:value pair in Python dictionary, then using a for loop, for each item of list, count its occurrence in tuple and sum them.




# Python3 Program to count occurrence 
# of all elements of list in a tuple
  
def countOccurrence(tup, lst):
    dct = {}
    for i in tup:
        if not dct.get(i):
            dct[i] = 0
        dct[i] += 1
    return sum(dct.get(i, 0) for i in lst)
      
# Driver Code
tup = ('a', 'a', 'c', 'b', 'd')
lst = ['a', 'b']
print(countOccurrence(tup, lst))
Output:
3

 
Approach #5 : Python numpy.in1d()
Python numpy gives us a direct method to find the solution for the given problem, and that is numpy.in1d(). This method test whether each element of a 1-D array is also present in a second array. Since list is also a 1-D array, this method can be applied here.




# Python3 Program to count occurrence 
# of all elements of list in a tuple
import numpy as np
  
def countOccurrence(tup, lst):
    return np.in1d(tup, lst).sum()
      
# Driver Code
tup = ('a', 'a', 'c', 'b', 'd'
lst = ['a', 'b']
print(countOccurrence(tup, lst))
Output:
3



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