Question :
I’m parsing JSON objects and found this sample line of code which I kind of understand but would appreciate a more detailed explanation of:
for record in [x for x in records.split("n") if x.strip() != '']:
I know it is spliting records to get individual records by the new line character however I was wondering why it looks so complicated? is it a case that we can’t have something like this:
for record in records.split("n") if x.strip() != '']:
So what do the brackets do []? and why do we have x twice in x for x in records.split....
Thanks
Answer #1:
The “brackets” in your example constructs a new list from an old one, this is called list comprehension.
The basic idea with [f(x) for x in xs if condition] is:
def list_comprehension(xs):
result = []
for x in xs:
if condition:
result.append(f(x))
return result
The f(x) can be any expression, containing x or not.
Answer #2:
That’s a list comprehension, a neat way of creating lists with certain conditions on the fly.
You can make it a short form of this:
a = []
for record in records.split("n"):
if record.strip() != '':
a.append(record)
for record in a:
# do something
Answer #3:
The square brackets ( [] ) usually signal a list in Python.
