PYTHON

count number of occurrences of all elements in list python

import collections

a_list = ["a", "b", "a"]
occurrences = collections.Counter(a_list)
print(occurrences)

python find number of occurrences in list

student_grades = [9.1, 8.8, 10.0, 7.7, 6.8, 8.0, 10.0, 8.1, 10.0, 9.9]

samebnumber = student_grades.count(10.0)

print(samebnumber)

How to Count occurrences of an item in a list in python

from collections import Counter

1ist1 = ['Peter', 'Rose', 'Donald', 'Peter']
a = Counter(listl).get('Peter')

print(f'Peter appears in the list {a} times')

# Output:
# Peter appears in the list 2 times

find all occurrences of an element in a list python

indices = [index for index, element in enumerate(a_list) if element == 1]

find all occurrences of element in list

"""Find all occurrences of element in list"""

# If you simply want find how many times an element appears
# use the built-in function count()
def find_occur(lst, item):
	return lst.count(item)

# Test -----------------------------------------------------------
print(find_occur([None, None, 1, 2, 3, 4, 5], None)) # 2

# If you wanna find where they occur instead
# - This returns the indices where element is found within a list

def find(lst, item):
    return [i for (i, x) in enumerate(lst) if x == item]

# Test Code ------------------------------------------------------
from random import randint, choice
lst = [randint(0, 99) for x in range(10)] # random lst
item = choice(lst) # item to find
found = find(lst, item) # lst of where item is found at
print(f"lst: {lst}",
      f"item: {item}",
      f"found: {found}",
      sep = "
")

number of occurrences of element in list

Map<String, Long> counts =
    list.stream().collect(Collectors.groupingBy(e -> e, Collectors.counting()));