• p.shkadzko (29/29) Mar 10 2020 I need to reproduce numpy sort for 2D array.
• jmh530 (12/13) Mar 10 2020 Below does the same thing as the numpy version.
• 9il (15/28) Mar 10 2020 Almost the same, just fixed import for `each` and a bit polished
• Pavel Shkadzko (2/18) Mar 11 2020 Great, thanks guys!
• jmh530 (4/19) Mar 11 2020 Doh on the 'each' import.

p.shkadzko <p.shkadzko gmail.com> writes:

I need to reproduce numpy sort for 2D array.

----------------------------------
import numpy as np

a = [[1, -1, 3, 2], [0, -2, 3, 1]]
b = np.sort(a)
b


----------------------------------

Numpy sorted the array by columns, which visually looks like each 
row of elements was sorted individually.
Going through 
http://docs.algorithm.dlang.io/latest/mir_ndslice_sorting.html I 
couldn't find analogous operation.

So, attempting to do the same in mir.ndslice results in the 
following:

-----------------------------------------------
import mir.ndslice;

auto m = [1, -1, 3, 2, 0, -2, 3, 1].sliced(4, 2);
// [[1, -1], [3, 2], [0, -2], [3, 1]]

m.sort;
// [[-2, -1], [0, 1], [1, 2], [3, 3]]
-----------------------------------------------

It basically flattened the 2D slice, sorted and reshaped it back 
into 2D with elements being moved.
Trying to do something like m.map!(a => a.sort); won't work 
because "a" is an int "1" and not a slice of two ints "[1, -1]". 
You can do it with foreach loop but then you'll have to allocate 
new elements. How do you do it in-place with mir?

jmh530 <john.michael.hall gmail.com> writes:

On Tuesday, 10 March 2020 at 23:31:55 UTC, p.shkadzko wrote:
 [snip]

Below does the same thing as the numpy version.

/+dub.sdl:
dependency "mir-algorithm" version="~>3.7.18"
+/
import mir.ndslice.sorting : sort;
import mir.ndslice.topology : byDim;
import mir.ndslice.slice : sliced;

void main() {
     auto m = [1, -1, 3, 2, 0, -2, 3, 1].sliced(2, 4);
     m.byDim!0.each!(a => a.sort);
}

9il <ilyayaroshenko gmail.com> writes:

On Wednesday, 11 March 2020 at 00:24:13 UTC, jmh530 wrote:
 On Tuesday, 10 March 2020 at 23:31:55 UTC, p.shkadzko wrote:
 [snip]

 Below does the same thing as the numpy version.

 /+dub.sdl:
 dependency "mir-algorithm" version="~>3.7.18"
 +/
 import mir.ndslice.sorting : sort;
 import mir.ndslice.topology : byDim;
 import mir.ndslice.slice : sliced;

 void main() {
     auto m = [1, -1, 3, 2, 0, -2, 3, 1].sliced(2, 4);
     m.byDim!0.each!(a => a.sort);
 }

Almost the same, just fixed import for `each` and a bit polished

/+dub.sdl:
dependency "mir-algorithm" version="~>3.7.18"
+/
import mir.ndslice;
import mir.ndslice.sorting;
import mir.algorithm.iteration: each;

void main() {
     auto m = [[1, -1, 3, 2],
               [0, -2, 3, 1]].fuse;
     m.byDim!0.each!sort;

     import std.stdio;
     m.byDim!0.each!writeln;
}

Pavel Shkadzko <p.shkadzko gmail.com> writes:

On Wednesday, 11 March 2020 at 06:12:55 UTC, 9il wrote:
 On Wednesday, 11 March 2020 at 00:24:13 UTC, jmh530 wrote:
 [...]

 Almost the same, just fixed import for `each` and a bit polished

 /+dub.sdl:
 dependency "mir-algorithm" version="~>3.7.18"
 +/
 import mir.ndslice;
 import mir.ndslice.sorting;
 import mir.algorithm.iteration: each;

 void main() {
     auto m = [[1, -1, 3, 2],
               [0, -2, 3, 1]].fuse;
     m.byDim!0.each!sort;

     import std.stdio;
     m.byDim!0.each!writeln;
 }

Great, thanks guys!

jmh530 <john.michael.hall gmail.com> writes:

On Wednesday, 11 March 2020 at 06:12:55 UTC, 9il wrote:
 [snip]

 Almost the same, just fixed import for `each` and a bit polished

 /+dub.sdl:
 dependency "mir-algorithm" version="~>3.7.18"
 +/
 import mir.ndslice;
 import mir.ndslice.sorting;
 import mir.algorithm.iteration: each;

 void main() {
     auto m = [[1, -1, 3, 2],
               [0, -2, 3, 1]].fuse;
     m.byDim!0.each!sort;

     import std.stdio;
     m.byDim!0.each!writeln;
 }

Doh on the 'each' import.

Also, I don't think I had used fuse before. That's definitely 
helpful.