Condensing code in Python with Mappings

Question

I seem to be using this block of code alot in Python.

if Y is not None:
    obj[X][0]=Y

How do I establish a mapping from X=>Y and then iterate through this entire mapping while calling that block of code on X and Y

Answer 1

If Y is None, you can do something like:

default_value = 0
obj[X][0] = Y if not None else default_value

Answer 2

mapping = {X1: Y1, X2: Y2, X3: Y3}
mapping[X4] = Y4
mapping[X5] = Y5

for X,Y in mapping.items():
    if Y is not None:
        obj[X][0] = Y