Add elements in a list Python

Question

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.

Please provide an example of the desired output for this input; in particular, it isn't clear what adding you wish to do. — Scott Hunter
– Scott Hunter, Commented Nov 23, 2014 at 17:33

Ashwini Chaudhary · Accepted Answer · 2014-11-23 17:53:22Z

1

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.

edited Nov 23, 2014 at 17:53

answered Nov 23, 2014 at 17:47

Ashwini Chaudhary

252k60 gold badges478 silver badges519 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Jake0x32 · Accepted Answer · 2014-11-23 17:34:42Z

1

for item in under_list:
    item_ = filter(lambda x: x != None and x >= 50, under_list)
    # Here compute sum of item_ and append to the right place

answered Nov 23, 2014 at 17:34

Jake0x32

1,4322 gold badges11 silver badges18 bronze badges

Comments

wwii · Accepted Answer · 2014-11-23 18:10:25Z

1

Write a function to return what you need:

def foo(thing):
    try:
        return sum(thing)
    except TypeError:
        return thing[0]

map the function to the zipped rows of under__list

>>> 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']]

>>> map(foo, zip(*under__list))
[118, 1.0604517619400802, None, None, 24, 2.0896934739352395, 0.683038507240796, 1.8219672937331732, 4.672749414021146, 3.2147023373942214, 20051, 0, 65, None, ' >50K']
>>>

edited Nov 23, 2014 at 18:10

answered Nov 23, 2014 at 17:58

wwii

23.9k7 gold badges42 silver badges80 bronze badges

Collectives™ on Stack Overflow

Add elements in a list Python

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related