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+--- Thread: How to sum array of numbers in Ruby? (/Thread-How-to-sum-array-of-numbers-in-Ruby)
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How to sum array of numbers in Ruby? - officiationru - 07-18-2023
I have an array of integers.
For example:
array = [123,321,12389]
Is there any nice way to get the sum of them?
I know, that
sum = 0
array.each { |a| sum+=a }
would work.
RE: How to sum array of numbers in Ruby? - boxfishvhnifhud - 07-18-2023
Alternatively (just for comparison), if you have Rails installed (actually just ActiveSupport):
require 'activesupport'
array.sum
RE: How to sum array of numbers in Ruby? - ob348 - 07-18-2023
ruby 1.8.7 way is the following:
array.inject(0, &:+)
RE: How to sum array of numbers in Ruby? - Liping868219 - 07-18-2023
Also allows for `[1,2].sum{|x| x * 2 } == 6`:
#
[To see links please register here]
class Arraydef sum(method = nil, &block)
if block_given?
raise ArgumentError, "You cannot pass a block and a method!" if method
inject(0) { |sum, i| sum + yield(i) }
elsif method
inject(0) { |sum, i| sum + i.send(method) }
else
inject(0) { |sum, i| sum + i }
end
end
end
RE: How to sum array of numbers in Ruby? - steelworker99784 - 07-18-2023
Just for the sake of diversity, you can also do this if your array is not an array of numbers, but rather an array of objects that have properties that are numbers (e.g. amount):
array.inject(0){|sum,x| sum + x.amount}
RE: How to sum array of numbers in Ruby? - saiger - 07-18-2023
You can also do it in easy way
def sum(numbers)
return 0 if numbers.length < 1
result = 0
numbers.each { |num| result += num }
result
end
RE: How to sum array of numbers in Ruby? - gibus101423 - 07-18-2023
You can use *.map* and *.sum* like:
array.map { |e| e }.sum
RE: How to sum array of numbers in Ruby? - unrepudiable599253 - 07-18-2023
array.reduce(0, :+)
While equivalent to `array.inject(0, :+)`, the term **reduce** is entering a more common vernacular with the rise of [MapReduce programming models][1].
**inject**, **reduce**, **fold**, **accumulate**, and **compress** are all synonymous as a class of [folding functions][2]. I find consistency across your code base most important, but since various communities tend to prefer one word over another, it’s nonetheless useful to know the alternatives.
To emphasize the map-reduce verbiage, here’s a version that is a little bit more forgiving on what ends up in that array.
array.map(&:to_i).reduce(0, :+)
Some additional relevant reading:
-
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[1]:
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RE: How to sum array of numbers in Ruby? - unelusive423581 - 07-18-2023
Ruby 2.4.0 is released, and it has an [Enumerable#sum][1] method. So you can do
array.sum
Examples from the docs:
{ 1 => 10, 2 => 20 }.sum {|k, v| k * v } #=> 50
(1..10).sum #=> 55
(1..10).sum {|v| v * 2 } #=> 110
[1]:
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RE: How to sum array of numbers in Ruby? - bonninesses516252 - 07-18-2023
# New for Ruby 2.4.0
You can use the aptly named method `Enumerable#sum`. It has a lot of advantages over `inject(:+)` but there are some important notes to read at the end as well.
## Examples
### Ranges
(1..100).sum
#=> 5050
### Arrays
[1, 2, 4, 9, 2, 3].sum
#=> 21
[1.9, 6.3, 20.3, 49.2].sum
#=> 77.7
## Important note
This method is not equivalent to `#inject(:+)`. For example
%w(a b c).inject(:+)
#=> "abc"
%w(a b c).sum
#=> TypeError: String can't be coerced into Integer
Also,
(1..1000000000).sum
#=> 500000000500000000 (execution time: less than 1s)
(1..1000000000).inject(:+)
#=> 500000000500000000 (execution time: upwards of a minute)
See [this answer](
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) for more information on why `sum` is like this.