python where in list
Checking if something is inside
Checking whether something is inside a list or not.You can use the in operator.
3 in [1, 2, 3] # => True
python find in list
Filtering a collection
Finding all elements in a sequence that meet a certain condition. You can use list comprehension or generator expressions for that
matches = [x for x in lst if fulfills_some_condition(x)] matches = (x for x in lst if x > 6)
Finding the location of an item
[1,2,3].index(2) # => 1 [1,2,3].index(4) # => ValueError
python list find
if you have duplicates, .index always returns the lowest index
[1,2,3,2].index(2) # => 1
python search list
Finding the first occurrence
If you only want the first thing that matches a condition (but you don’t know what it is yet), it’s fine to use a for loop
next(x for x in lst if ...) next((x for x in lst if ...), [default value])
If there are duplicates and you want all the indexes then you can use enumerate()
[i for i,x in enumerate([1,2,3,2]) if x==2] # => [1, 3]