Sum numbers in an array

Question

I'm a Python newbie.

At this site, they show how to sum list of integers.

What if instead of a list of raw ints, you had a list of

class Number :
   def __init__( self, x = 0) :
      self.number = x      

   def getNumber( self ) :
      return self.number

What's the Python code to sum the self.number in an array in a few lines (hopefully)?

Answer 1

Try this:

sum(x.getNumber() for x in l)

By the way, [1, 2, 3]is a list, not an array.

Answer 2

Use a generator or list comprehension:

numbers = [Number(1), Number(2)]
sum(n.getNumber() for n in numbers)

Simply, it calls the method getNumber() on each item before summing.

Answer 3

I am assuming you mean a list or maybe another kind of iterable:

sum(x.getNumber() for x in L)

Answer 4

Here are several ways to do it:

sum( e.getNumber() for e in L )

sum( e.number for e in L )

reduce( lambda a,b: a + b.getNumber(), L, 0 )  # likewise for e.number