array x array? July 18th, 2008
Tom(warning: non-english blog) had a small friday-afternoon problem for me, which they couldn’t easily figure out. The problem:
x = [1, 2, 3] y = ['a', 'b', 'c'] ??? # result should == [[1,'a'],[2,'b'],[3,'c']]
My first guess was a simple * but apparently Array#* only takes strings and numbers:
x * 3 # => [1, 2, 3, 1, 2, 3, 1, 2, 3] x * '-' # => "1-2-3" x * y # => TypeError: can't convert Array into Integer
So I went through the Array API and found out there was something like transpose. Basically this is what you want:
x = [1, 2, 3] y = ['a', 'b', 'c'] result = [x,y].transpose # => [[1, "a"], [2, "b"], [3, "c"]]
update!
As Jean-Baptiste notes in the comments, there is also the zip function
[1, 2, 3].zip(['a', 'b', 'c']) # => [[1, "a"], [2, "b"], [3, "c"]]
Transpose isn’t that special, it sort of mirrors a matrix over its main diagonal (you can see the [x,y] array as a matrix [[1,2,3],[a,b,c]].
More on the wikipedia page: http://en.wikipedia.org/wiki/Transpose
multipling arrays with each other isn’t that easy when not thinking in terms of matrixes
Actually, I think there is a method intended to do that:
In your case, it would be an elegant:
x.zip(y)
You can even do
“w.zip(x,y,z)”
provided w, x, y and z are Arrays.