On Aug 1, 9:37 am, beginner <[EMAIL PROTECTED]> wrote:
> Hi,
>
> Does anyone know how to put an assertion in list comprehension? I have
> the following list comprehension, but I want to use an assertion to
> check the contents of rec_stdl. I ended up using another loop which
> essentially duplicates the functions of list comprehension. It just
> look like a waste of coding and computer time to me.
>
> I just wish I could put the assertions into list comprehensions.
>
> x=[(rec_stdl[0].st/10000.0,
> rec_stdl[0].cl,
> rec_stdl[0].bb,
> rec_stdl[0].bo,
> rec_stdl[1].bb,
> rec_stdl[1].bo,
> rec_stdl[0].ex
> )
> for rec_stdl in rec_by_ex if len(rec_stdl)==2
> ]
>
> #duplicated loop
> if __debug__:
> for rec_stdl in rec_by_ex:
> l=len(rec_stdl)
> assert(l<=2 and l>0)
> if l==2:
> assert(rec_stdl[0].c=="C" and rec_stdl[1].c=="P")
> assert(rec_stdl[0].ex==rec_stdl[1].ex)
> assert(rec_stdl[0].st==rec_stdl[1].st)
> assert(rec_stdl[0].cp==rec_stdl[1].cp)
>
> Thanks,
> Geoffrey
Can't you just call a function from within your list comprehension and
do whatever you want for each item? Something like this (not tested):
def checker(item):
assert(len(item) <= 2 and len(item) > 0)
if len(item) == 2:
assert(item[0].c == "C" and item[1].c == "P"
return len(item) == 2
x = [whatever for item in all_items if checker(item = item)]
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