listcomp.py

print [x**2 for x in range(10)]

# single conditional
print [x**2 for x in range(10) if x % 2 == 0]

# single not conditional
print [x**2 for x in range(10) if not x % 2 == 0]

# nested for
for a in [[x, y, z] for x in [1,2,3] for y in "abc" for z in "xyz" ]:
    print a

# nested for with conditional
print [[x, y] for x in [1,2,3] for y in [3,1,4] if x != y]

# nested conditionals
print [[y,z] for y in range(100) if y % 2 == 0 if y % 5 == 0 for z in "ab"]


# nested list comprehension
matrix = [ [1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12] ]

# this is a tricky case because matrix is defined outside generator function.
print [[row[i] for row in matrix ] for i in range(4)]

# this presently is a simpler case, but still tricky because i is defined in
# generator function 1, and row[i] is used in generator function 2, where i is undefined.
print [[row[i] for row in [ [1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12] ]  ] for i in range(4)]