List Comprehension in Python (listcomps)

comprehension.py

# Notes:
# List comprehension (listcomps) is an expression.
# With list comprehension, you get back a list, not a generator.
# With generator expression, you get back an iterator that computes values as an when needed.

# prints [1, 2, 3, 4]
[x for x in (1, 2, 3, 4)]

# prints [2, 4]
[x for x in (1, 2, 3, 4) if x % 2 == 0]

# prints [(1, 'a'), (1, 'b'), (2, 'a'), (2, 'b'), (3, 'a'), (3, 'b'), (4, 'a'), (4, 'b')]
[(x, y) for x in (1, 2, 3, 4) for y in ['a', 'b']]

# prints [(2, 'b'), (4, 'b')]
[(x, y) for x in (1, 2, 3, 4) if x % 2 == 0 for y in ['a', 'b'] if y == 'b']