Back to Questions
973
views2
comments
Converting Array2 to "list list"
f#

Hey guys,

Lately I've needed to convert an Array2 to a list of lists.

Essentially, the elements in each row in the Array2 needed to be grouped into its own list, and each of those lists needed to be grouped into another list (of rows).

Here's my first attempt:

1
2

let array2ToListlist (a:'a[,]) =
  [0..(Array2.length1 a)-1] |> List.map (fun r -> [0..(Array2.length2 a)-1] |> List.map (fun c -> a.[r,c]));

Is there a better way? I didn't see any Array2.to_listlist or List.of_Array2, etc.

Any ideas? :)

.

I don't have the answer to your question, but you'd better take "base" into consideration:

1
2
3
4

let a2l a =
  let x0,y0 = Array2.base1 a, Array2.base2 a in
  let x1,y1 = x0 + Array2.length1 a - 1, y0 + Array2.length2 a - 1 in
  [for x in x0..x1 -> [for y in y0..y1 -> a.(x,y)]];;
By on 1/5/2008 2:07 PM ()

Thanks a bunch for that. :)

I guess I didn't realize that you could set the base (like 0- or 1-indexed) of the Array2 data structure.

And I keep forgetting about the list comprehensions! Man those are nice.

By on 1/5/2008 2:53 PM ()

    Topic tags

    IntelliFactory Offices Copyright (c) 2011-2012 IntelliFactory. All rights reserved.
    Home | Products | Consulting | Trainings | Blogs | Jobs | Contact Us | Terms of Use | Privacy Policy | Cookie Policy     		Built with WebSharper