digitalmars.D.learn - Using std.algorithm how to uniq and sort a multidimensional array?
- Gary Willoughby (6/6) Jan 28 2014 Using std.algorithm how to uniq and sort a multidimensional array?
- Gary Willoughby (4/11) Jan 28 2014 Gah, it was simpler than i thought, of course.
- bearophile (18/20) Jan 28 2014 I think the right abstraction for your use case is:
- Meta (2/8) Jan 28 2014 auto tags = tags.flatMap!uniq.array ?
- bearophile (7/8) Jan 29 2014 That's another solution. In Phobos a flatMap can be useful (just
Using std.algorithm how to uniq and sort a multidimensional array? e.g. the uniq function takes a function as a predicate but i'm confused how to handle the multiple dimensions. string[][] tags; tags = tags.uniq!("a[0][1] == b[1][1]").array; The above is my attempt and it failed.
Jan 28 2014
On Tuesday, 28 January 2014 at 14:46:48 UTC, Gary Willoughby wrote:Using std.algorithm how to uniq and sort a multidimensional array? e.g. the uniq function takes a function as a predicate but i'm confused how to handle the multiple dimensions. string[][] tags; tags = tags.uniq!("a[0][1] == b[1][1]").array; The above is my attempt and it failed.Gah, it was simpler than i thought, of course. tags = tags.sort!("a[1] < b[1]").uniq!("a[1] == b[1]").array;
Jan 28 2014
Gary Willoughby:string[][] tags; tags = tags.uniq!("a[0][1] == b[1][1]").array;I think the right abstraction for your use case is: auto tags = tags.flatten.uniq.array; Where a std.range.flatten should take a range, range of ranges, range of range of ranges, etc, and yield the items scanning them by rows (flatten takes a template argument enumeration to change the scanning pattern: by rows, by columns, bidirectional rows, zig-zag, Hamming curve, Z curve, 2D rectangular blocks). Probably flatten should have a compile-time argument to tell it what a iterable range means. And an optional run-time argument "maxDepth". Ideally flatten should yield references of the items, so you can increase all matrix items by 1 with code like: int[][][] matrix = ...; foreach (ref item; mat.flatten) item++; Bye, bearophile
Jan 28 2014
On Tuesday, 28 January 2014 at 15:07:26 UTC, bearophile wrote:Gary Willoughby:auto tags = tags.flatMap!uniq.array ?string[][] tags; tags = tags.uniq!("a[0][1] == b[1][1]").array;I think the right abstraction for your use case is: auto tags = tags.flatten.uniq.array;
Jan 28 2014
Meta:auto tags = tags.flatMap!uniq.array ?That's another solution. In Phobos a flatMap can be useful (just as a zip overload that accepts a function to apply on the pairs, named zipWith in haskell: http://zvon.org/other/haskell/Outputprelude/zipWith_f.html ). Bye, bearophile
Jan 29 2014