I am curious to know what is faster in Python
Say I have a list
myList = ['a', 'b', 'c', 'd', 'e']
I have two ways of checking if an item is in the list.
if item in myList:
# doSomthing()
or
for element in myList:
if element == item:
# doSomething()
I know that the first method is more "pythonic" but in terms of performance is there a difference?
Testing in jupyter notebook, the first option is significantly faster for a string search:
Setup (from this question):
rndm=''.join(choices(string.ascii_uppercase + string.digits, k=100000))
Tests:
%timeit 'a' in rndm
26.2 µs ± 485 ns per loop
%%timeit
for let in rndm:
if let=='a':
break
2.42 ms ± 73.7 µs per loop
Note: Even if we make a set() out of rndm and time the search, it still only comes in at 1.14 ms ± 26.9 µs per loop
Case 1:
if item in myList:
This will take O(1) time for N values.
O(1) means it will take the same time for N number of values, If your list has 1000 entries or 10 Lacs entries time taken by case 1 is the same.
Case 2:
for element in myList:
if element == item:
This will take O(log(n)) time N values.
O(log(n)) means it will expressly time for N number of values, time will increase when the List has more values.
breakin yourforloop. The loop also has to create a binding (element) that the first version doesn't.breakon purpose, obviously I can add one. With it in is the performance the same?