CODEWITHSUNDEEP
pythonlist-comprehension
mathandy
mathandy

Reputation: 2010

print (or execute statements) inside python list comprehension

I'm wondering if there is any way to print (or, more generally, execute statements) inside a list comprehension.
So we're all on the same page, consider the list comprehension inside the following function, f:

def g(x):
     return some_complicated_condition_function(x)

def f(list_of_numbers,n):
     return [i for i in range(n) if g(list_of_numbers[i]) > 0]

Say I get some mysterious error when calling f and want to debug by catching the error using something like:

try: g(list_of_numbers[i])
except: 
    print (i,list_of_numbers[i]))
    raise Exception("Danger Will Robinson!")

Is there anyway to do this without rewriting my list comprehension as a traditional for/while loop?

Thanks! P.S. Maybe this is a horrible way to debug (I'm math, not CS), so if you have any tips don't be shy.

Upvotes: 5

Views: 1607

Answers (1)

mathandy
mathandy

Reputation: 2010

Whoops, so I realized the answer to this after posting it! >:O

I just need to make another function:

def h(i,list_of_numbers):
    try: g(list_of_numbers[i])
    except: 
        print (i,list_of_numbers[i]))
        raise Exception("Danger Will Robinson!")
return i

Then I can just make my list comprehension:

[h(i) for i in range(n) if g(list_of_numbers[i]) > 0]

...and I guess that technique should work for executing any statement I want. Darn, I was so excited to finally have something to post on stack exchange!

Upvotes: 2

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