I was trying to convert the itertools.product() python's fonction to C code:
def product(*args, repeat=1):
pools = [tuple(pool) for pool in args] * repeat
result = [[]]
for pool in pools:
result = [x+[y] for x in result for y in pool]
for prod in result:
yield tuple(prod)
to C code, but I didn't understand this particular instruction:
result = [x+[y] for x in result for y in pool]
could anyone explain it for me ? thank's
As Ashish pointed out, it's a list comprehension. In short list comprehensions are basically just a one-liner for a loop with an optional conditional statement (or many conditional statements for that matter) that returns an array.
[ expression for item in list if conditional ]
is equivalent to
for item in list:
if conditional:
expression
List comprehensions will return an array of all expression results in that loop.
result = [ x+1 for x in [0,1,2] ]
would in turn execute 0+1, save the value in an array, then do the same with 1+1 and 2+1. Finally the result would be [1,2,3]
It's a list comprehension. It is equivalent to the following -
result = []
for x in result:
for y in pool:
result.append(x+[y])
