Hi

I am trying to generate 2 arrays which is modifications of clist. But I am having some problems, how would you do it ?


#!/usr/bin/rdmd
import std.stdio;
import std.algorithm;

void main()
{

 bool[][][] clist=[[[true, true], [false, true]],[[true, false], [true,
true]],[[false, true], [true, true]]];

 auto x=0;
writeln(clist);

auto fpos=delegate bool(bool[][] a){return(a[x]!=[true,false]);};
auto fneg=delegate bool(bool[][] a){return(a[x]!=[false,true]);};
 writeln("pos:",map!(delegate (bool[][] a){a[x][0]=true; return
a;})(filter!(fpos)(clist)));
 writeln("neg:",map!(delegate (bool[][] a){a[x][1]=true; return
a;})(filter!(fneg)(clist)));


}
The code outputs:

[[[true, true], [false, true]], [[true, false], [true, true]], [[false,
true], [true, true]]]
pos:[[[true, true], [false, true]], [[true, true], [true, true]]]
neg:[[[true, true], [false, true]], [[true, true], [true, true]],[[true,
true], [true, true]]]

But I should be

[[[true, true], [false, true]], [[true, false], [true, true]], [[false,
true], [true, true]]]
pos:[[[true, true], [false, true]], [[true, true], [true, true]]]
neg:[[[true, true], [false, true]], [[true, true], [true, true]]]

Hope you can help.

On Monday, 18 March 2013 at 07:27:21 UTC, Knud Soerensen wrote:
> Hi
>
> I am trying to generate 2 arrays which is modifications of clist.
> But I am having some problems, how would you do it ?
>
>
> #!/usr/bin/rdmd
> import std.stdio;
> import std.algorithm;
>
> void main()
> {
>
>  bool[][][] clist=[[[true, true], [false, true]],[[true, false], [true,
> true]],[[false, true], [true, true]]];
>
>  auto x=0;
> writeln(clist);
>
> auto fpos=delegate bool(bool[][] a){return(a[x]!=[true,false]);};
> auto fneg=delegate bool(bool[][] a){return(a[x]!=[false,true]);};
>  writeln("pos:",map!(delegate (bool[][] a){a[x][0]=true; return
> a;})(filter!(fpos)(clist)));
>  writeln("neg:",map!(delegate (bool[][] a){a[x][1]=true; return
> a;})(filter!(fneg)(clist)));
>
>
> }
> The code outputs:
>
> [[[true, true], [false, true]], [[true, false], [true, true]], [[false,
> true], [true, true]]]
> pos:[[[true, true], [false, true]], [[true, true], [true, true]]]
> neg:[[[true, true], [false, true]], [[true, true], [true, true]],[[true,
> true], [true, true]]]
>
> But I should be
>
> [[[true, true], [false, true]], [[true, false], [true, true]], [[false,
> true], [true, true]]]
> pos:[[[true, true], [false, true]], [[true, true], [true, true]]]
> neg:[[[true, true], [false, true]], [[true, true], [true, true]]]
>
> Hope you can help.

First writeln() actually edit the original array, so when you filter it for the second array, fneg gives true for all clist[][][] elements.

> First writeln() actually edit the original array, so when you filter it for the second array, fneg gives true for all clist[][][] elements.

How would you get around this ?

On Monday, 18 March 2013 at 09:15:50 UTC, Knud Soerensen wrote:
>
>> First writeln() actually edit the original array, so when you filter it
>> for the second array, fneg gives true for all clist[][][] elements.
>
> How would you get around this ?

You should work on a whole copy of clist array.
Or return copy of elements from map function instead of the element itself (<-- faster and lazy solution, i guess)

To get a whole copy you can try to do something like this:

T recursiveDup(T)(ref T array) if (isArray!T)
{
	T retVal = array.dup;
	foreach(ref e; retVal)
		static if (isArray!(typeof(e)))
			e = recursiveDup(e);

	return retVal;
}

gives you a copy of your array. It's a simple code, that works just for your specific case - not so efficient :)