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up vote 3 down vote favorite

I want to do something like this:

a = some_funct()
b = [ 1, a if a is not None ]

The list b should be one element long if a is None, and two elements long if a is not None. Is this possible in Python or do I have to use a separate if check followed by add()?

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2  
How about b = [1]; if a is not None: b.append(a)? – Psidom 18 hours ago
    
Alternatively, b = [x for x in (1, a) if x is not None] ... but check-then-append is going to be more readable. – Zero Piraeus 18 hours ago
    
b=[1];a and b.append(a) ??? – Skycc 18 hours ago
up vote 3 down vote

Doesn't look the best, but you could do

b = [1] + ([a] if a is not None else [])

Of course, it would be better to check as it increases code readability.

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up vote 2 down vote 
a = some_funct()
b = [ 1, a ] if a is not None else [1]
share|improve this answer
up vote 1 down vote

You can do this using list comprehension

b = [x for x in (1, a) if x is not None]

The tuple (1, a) is the total set, b will become a list of all elements in that total set which are not None

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