Python count function - Get the number of item in a list
You can get the occurrence of an item in a list.
p = ['a', 'a', 'a', 'b', 'c', 'c']
i = p.count('a')
print(i) # 3
count returns the number of a in p. There are 3 a in p so 3 is returned.
Python count and len are confusing as follows.
p = ['a', 'a', 'a', 'b', 'c', 'c']
i = p.count('a')
j = len(p)
print(i) # 3
print(j) # 6
No item, 0 count
If the list doesn't contain the item, count returns 0.
p = ['a', 'a', 'a', 'b', 'c', 'c']
i = p.count('d')
print(i) # 0
There is no d in p list so count returns 0.
If an item is a list...
count works for a list, set, dictionary, and so on.
a = [1, [2, 3], 'car']
c = a.count([2, 3])
print(c) # 1
a has actually [2, 3] but doesn't have 2 itself. [2, 3] and 2 are essentially different in Python.
a = [1, [2, 3], 'car']
c = a.count(2)
print(c) # 0
Substring occurrence
You can use count to count how many times the substring occurs in a string.
s = 'aabbbcccc'
a = s.count('a')
b = s.count('b')
c = s.count('c')
print(a) # 2
print(b) # 3
print(c) # 4