Derek MC Derek MC -4 years ago 76
Python Question

Add elements in a list Python

under__list =[[74, 0.1423287845938018, None, None, 10,
1.9099604642265018, 0.5185563065935468, 1.6825659992347914,
3.547506695574544, 2.7789822726693023, 20051, 0, 25, None, ' >50K'],
[44, 0.9181229773462783, None, None, 14, 0.17973300970873787,
0.1644822006472492, 0.13940129449838187, 1.1252427184466018,
0.4357200647249191, 0, 0, 40, None, ' <=50K']]


I have the above list but I want to add the elements together but skip past the
None
and the
">=50"
elements.

I want to be able to do it even if I don't know where
None
number values are.
Any suggestions?

for item in zip(under__list[row]):
under__list.append(int(sum(item[0])))


Looking for the below output:

[1182, 25.2452245, None, None, 9212, 256, 2624, 25.24,
2532, 25, 2005252, 52, 25632, None, ' >50K']


It would be one list with numbers added together.

Answer Source

It looks like you want to sum the items on the same indices from all inner lists. For that first of all you need to use zip with *, and then in the list comprehension check of the first item of each row is an instance of Number type or simply int or float(isinstance(x[0], (int, float))), if yes, sum them else use the first items as value.

>>> from numbers import Number
>>> [sum(x) if isinstance(x[0], Number) else x[0] for x in zip(*under__list)]
[118, 1.0604517619400802, None, None, 24, 2.0896934739352395, 0.683038507240796, 1.8219672937331732, 4.672749414021146, 3.2147023373942214, 20051, 0, 65, None, ' >50K']

The expression sum(x) if isinstance(x[0], Number) else x[0] is called a conditional expression.

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