Python Equivalent Of Ruby's .select

I have an list/array, lets call it x, and I want to create a new list/array, lets call this one z, out of elements from x that match a certain condition. In Ruby you could do that

Solution 1:

Python has a built-in filter function:

lst = [1, 2, 3, 4, 5, 6]
filtered = filter(lambda x: x < 5, lst)

But list comprehensions might flow better, especially when combining with map operations:

mapped_and_filtered = [x*2 for x in lst if x < 5]
# compare to:mapped_and_filtered = map(lambda y: y*2, filter(lambda x: x < 5, lst))

Solution 2:

One option is to use list comprehension:

>>> [a for a in x if a < 5][1, 2, 3, 4]

Solution 3:

Using a list comprehension is considered "Pythonic":

x = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
z = [i for i in x if i < 5]
print z

Output

[1, 2, 3, 4]