Reduce, fold or scan (Left/Right)?
When should I use reduceLeft, reduceRight, foldLeft, foldRight, scanLeft or scanRight? I want an intuition/overview of their differences – possibly with some simple … Read more
reduce
How to map/reduce/filter a Set in JavaScript?
Is there any way to map/reduce/filter/etc a Set in JavaScript or will I have to write my own? Here’s some sensible Set.prototype extensions … Read more
NameError: name ‘reduce’ is not defined in Python
I’m using Python 3.2. Tried this: xor = lambda x,y: (x+y)%2 l = reduce(xor, [1,2,3,4]) And got the following error: l = reduce(xor, … Read more
Javascript reduce() on Object
There is nice Array method reduce() to get one value from the Array. Example: [0,1,2,3,4].reduce(function(previousValue, currentValue, index, array){ return previousValue + currentValue; }); … Read more
How to call reduce on an array of objects to sum their properties?
Say I want to sum a.x for each element in arr. arr = [ { x: 1 }, { x: 2 }, { … Read more
How to use filter, map, and reduce in Python 3
filter, map, and reduce work perfectly in Python 2. Here is an example: >>> def f(x): return x % 2 != 0 and … Read more
Finding the average of a list
I have to find the average of a list in Python. This is my code so far from functools import reduce l = … Read more