Python | Check if k occurs atleast n times in a list
There are many common problems that a developer or common programmer comes across in day-day coding. One such problem is finding if an element occurs more than a certain number of times in the list. Let’s discuss certain ways to deal with this problem.
Method #1 : Using sum() + list comprehension
The list comprehension can be clubbed with the sum function for achieving this particular task. The sum function does the summation part and the logical case of returning true is dealt in list comprehension part.
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# Python3 code to demonstrate # check for minimum N occureneces of K # using sum() + list comprehension # initializing listtest_list = [1, 3, 5, 5, 4, 5] # printing original listprint ("The original list is : " + str(test_list)) # initializing k k = 5 # initializing NN = 3 # using sum() + list comprehension# checking occurrences of K atleast N times res = 0res = sum([1 for i in test_list if i == k]) >= Nif res == 1 : res = Trueelse : res = False # printing result print ("Does %d occur atleast %d times ? :" %(k, N) + str(res)) |
The original list is : [1, 3, 5, 5, 4, 5] Does 5 occur atleast 3 times ? : True
Method #2 : Using next() + islice()
These both functions can be used together to perform this particular task in more efficient manner than above. The islice function would handle the summation part and next function helps with iteration logic.
# Python3 code to demonstrate # check for minimum N occureneces of K # using next() + islice()from itertools import islice # initializing listtest_list = [1, 3, 5, 5, 4, 5] # printing original listprint ("The original list is : " + str(test_list)) # initializing k k = 5 # initializing NN = 3 # using next() + islice()# checking occurrences of K atleast N times func = (True for i in test_list if i == k)res = next(islice(func, N-1, None), False) # printing result print ("Does %d occur atleast %d times ? :" %(k, N) + str(res)) |
The original list is : [1, 3, 5, 5, 4, 5] Does 5 occur atleast 3 times ? : True
