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Are there some helpers in Phobos equivalent to std::set_difference of ugly c++
Feb 03, 2023
Ferhat Kurtulmuş
Feb 03, 2023
Ferhat Kurtulmuş
Feb 03, 2023
Ali Çehreli
Feb 03, 2023
Ali Çehreli
February 03, 2023
Gravatar of Ferhat KurtulmuşPosted by Ferhat KurtulmuşReply
Ferhat Kurtulmuş
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I could not find a thing doing this. And I don't want to write it from scratch. Getting a range as output is ok too. What I need is the following:

    const std::vector<int> v1{1, 2, 5, 5, 5, 9};
    const std::vector<int> v2{2, 5, 7};
    std::vector<int> diff;

    std::set_difference(v1.begin(), v1.end(), v2.begin(), v2.end(),
                        std::inserter(diff, diff.begin()));
    print(v1, "∖ ");
    print(v2, "= ");
    print(diff, "\n");

    // yielding { 1 2 5 5 5 9 } ∖ { 2 5 7 } = { 1 5 5 9 }
February 04, 2023
Gravatar of Richard (Rikki) Andrew CattermolePosted by Richard (Rikki) Andrew Cattermole
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Richard (Rikki) Andrew Cattermole
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```d
import std.stdio, std.algorithm.setops, std.array;

void main() {
    int[] v1 = [1, 2, 5, 5, 5, 9];
    int[] v2 = [2, 5, 7];
    int[] v3 = setDifference(v1, v2).array;

    writefln!"%s \\ %s = %s"(v1, v2, v3);
}
```

[1, 2, 5, 5, 5, 9] \ [2, 5, 7] = [1, 5, 5, 9]
February 03, 2023
Gravatar of Ferhat KurtulmuşPosted by Ferhat Kurtulmuş
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Ferhat Kurtulmuş
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On Friday, 3 February 2023 at 15:53:35 UTC, Richard (Rikki) Andrew Cattermole wrote:
> ```d
> import std.stdio, std.algorithm.setops, std.array;
>
> void main() {
>     int[] v1 = [1, 2, 5, 5, 5, 9];
>     int[] v2 = [2, 5, 7];
>     int[] v3 = setDifference(v1, v2).array;
>
>     writefln!"%s \\ %s = %s"(v1, v2, v3);
> }
> ```
>
> [1, 2, 5, 5, 5, 9] \ [2, 5, 7] = [1, 5, 5, 9]

Thank you very much. I am surprised that I couldn't find it using many keywords on the site and google.
February 04, 2023
Gravatar of Richard (Rikki) Andrew CattermolePosted by Richard (Rikki) Andrew Cattermole
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Richard (Rikki) Andrew Cattermole
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All good, I'm glad it'll work for you :)

I used the word difference to search the phobos docs with.
February 03, 2023
Gravatar of Ali ÇehreliPosted by Ali Çehreli
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Ali Çehreli
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On 2/3/23 08:01, Richard (Rikki) Andrew Cattermole wrote:
> All good, I'm glad it'll work for you :)
> 
> I used the word difference to search the phobos docs with.

'fold' is doing much better in that department because it mentions other names: "Implements the homonym function (also known as accumulate, compress, inject, or foldl) present in various programming languages of functional flavor."

  https://dlang.org/library/std/algorithm/iteration/reduce.html

Ali
February 03, 2023
Gravatar of Ali ÇehreliPosted by Ali Çehreli
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Ali Çehreli
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On 2/3/23 09:11, Ali Çehreli wrote:

> 'fold' is

Ha ha! :) Make that 'reduce' of course.

Ali