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| Subject | Re: Randomness in built-in .sort |
| From | bearophile <bearophileHUGS@lycos.com> |
| Date | Mon, 05 Jan 2009 20:18:21 -0500 |
| Newsgroups | digitalmars.D |
Bill Baxter: >I use this all the time in NumPy in the form of "argsort" which returns a list of indices giving the sort order. That can then be used as to index other arrays (thereby permuting them to the sorted order). order = npy.argsort(keys) sortedA = A[order] sortedB = B[order]< My dlibs already contain an efficient sorting routine, much faster than the built in one. So to my dlibs I have just added sortedIndexes and remapOrder, you can find their docs here: http://www.fantascienza.net/leonardo/so/dlibs/func.html The code: http://www.fantascienza.net/leonardo/so/libs_d.zip The usage is very simple, sortedIndexes is similar to sorted(): auto a = [-5, 2, 3, 1, -11].dup; auto order1 = a.sortedIndexes(); // now order1 == [4U, 0, 3, 1, 2] auto order2 = a.sortedIndexes((int x){return x < 0 ? -x : x;}); // Now order2 == [3U, 1, 2, 0, 4] int[2][] c = [[3, 4], [1,2], [1, 1]]; auto order3 = c.sortedIndexes(); // now order3 == [2U, 1, 0] auto a = [-5, 2, 3, 1, -11].dup; a.remapOrder([4, 0, 3, 1, 2]) ==> [-11, -5, 1, 2, 3] // a isn't changed here a.remapOrder([3, 1, 2, 0, 4]) ==> [1, 2, 3, -5, -11] auto b = ["oranges"[], "for", "apples", "is", "right"].dup; b.remapOrder([3, 1, 2, 0, 4]) ==> ["is"[], "for", "apples", "oranges", "right"].dup); (Maybe I have to rename remapOrder as remappedOrder). -------------------------------- While writing the unittest for those functions, I have seen this isn't accepted by DMD: int[2][] c = [[3, 4], [1, 2], [1, 1]].dup; While the compiler accepts this, I don't know why: int[2][] c0 = [[3, 4], [1, 2], [1, 1]]; int[2][] c2 = c0.dup; Bye, bearophile | |
