Re: Adjacent Pairs Range
On Monday, 14 September 2015 at 10:45:52 UTC, Per Nordlöw wrote: On Monday, 14 September 2015 at 05:37:05 UTC, Sebastiaan Koppe wrote: What about using zip and a slice? Slicing requires a RandomAccessRange (Array). This is too restrictive. We want to change operations such as adjacentTuples with for example map and reduce without the need for temporary copies of the whole range. This is the thing about D's standard library. Read up on D's range concepts. dropOne then. I saw your adjacentTuples. Two questions: a) can't you use a ringbuffer instead of copy when N > 2? b) shouldn't front() return a range over that ringbuffer?
Re: Adjacent Pairs Range
On Monday, 14 September 2015 at 05:37:05 UTC, Sebastiaan Koppe wrote: What about using zip and a slice? Slicing requires a RandomAccessRange (Array). This is too restrictive. We want to change operations such as adjacentTuples with for example map and reduce without the need for temporary copies of the whole range. This is the thing about D's standard library. Read up on D's range concepts.
Re: Adjacent Pairs Range
On Monday, 14 September 2015 at 10:45:52 UTC, Per Nordlöw wrote: restrictive. We want to change operations such as Correction: We want to *chain* operations such as...
Re: Adjacent Pairs Range
On Sunday, 13 September 2015 at 01:49:56 UTC, deed wrote: zip(arr[0 .. $-1], arr[1 .. $]) ? Assumes arrays. Better is zip(arr.dropOne, arr)
Re: Adjacent Pairs Range
On Saturday, 12 September 2015 at 10:17:19 UTC, Nordlöw wrote:
How do I most elegantly iterate all the adjacent pairs in an
`InputRange` using Phobos?
Something like
[1,2,3,4] => [(1,2), (2,3), (3,4)]
What about using zip and a slice?
```
void main()
{
auto a = [1,2,3,4];
import std.range : zip;
import std.stdio;
writeln(a.zip(a[1..$])); // [Tuple!(int, int)(1, 2), Tuple!(int,
int)(2, 3), Tuple!(int, int)(3, 4)]
}
```
Re: Adjacent Pairs Range
On Saturday, 12 September 2015 at 10:17:19 UTC, Nordlöw wrote: How do I most elegantly iterate all the adjacent pairs in an `InputRange` using Phobos? Something like [1,2,3,4] => [(1,2), (2,3), (3,4)] Why not just: zip(arr[0 .. $-1], arr[1 .. $]) ?
Re: Adjacent Pairs Range
On Saturday, 12 September 2015 at 10:35:41 UTC, Bahman Movaqar wrote: On 09/12/2015 02:47 PM, "Nordlöw" wrote: How do I most elegantly iterate all the adjacent pairs in an `InputRange` using Phobos? Something like [1,2,3,4] => [(1,2), (2,3), (3,4)] That's call `collate`ing IIRC. A quick solution would be using `std.range.transposed`: auto a = [1,2,3,4]; auto ll = [a, a[1..$]]; transpose(ll); // returns [[1, 2], [2, 3], [3, 4], [4]] InputRange please, not RandomAccessRanges ;)
Re: Adjacent Pairs Range
On 09/12/2015 02:47 PM, "Nordlöw" wrote: > How do I most elegantly iterate all the adjacent pairs in an > `InputRange` using Phobos? > > Something like > > [1,2,3,4] => [(1,2), (2,3), (3,4)] That's call `collate`ing IIRC. A quick solution would be using `std.range.transposed`: auto a = [1,2,3,4]; auto ll = [a, a[1..$]]; transpose(ll); // returns [[1, 2], [2, 3], [3, 4], [4]] Though you have to take care of the dangling last element yourself. -- Bahman Movaqar
Re: Adjacent Pairs Range
On 09/12/2015 04:04 PM, Bahman Movaqar wrote: > Oops! Here's one using only `InputRange` interface: I believe I need to warn you that I'm just learning D; so take my solution at your own risk :-) -- Bahman Movaqar
Re: Adjacent Pairs Range
On 09/12/2015 03:09 PM, "Nordlöw" wrote:
> InputRange please, not RandomAccessRanges ;)
Oops! Here's one using only `InputRange` interface:
T[][] collate(T)(T[] a)
{
alias CollateResult = Tuple!(T[][], "result", T, "tlHd");
CollateResult _collate(CollateResult collres)
{
if (!a.empty) {
auto newTlHd = a.front;
a.popFront();
return _collate(
CollateResult(
collres.result ~ [collres.tlHd, newTlHd],
newTlHd
)
);
} else {
return collres;
}
}
if (!a.empty) {
auto tlHd = a.front;
a.popFront();
return _collate(
CollateResult([], tlHd)
).result;
} else {
return [];
}
}
unittest {
writeln([10, 20, 30].collate!int);
}
--
Bahman Movaqar
Re: Adjacent Pairs Range
On Saturday, 12 September 2015 at 11:34:03 UTC, Bahman Movaqar wrote: On 09/12/2015 03:09 PM, "Nordlöw" wrote: InputRange please, not RandomAccessRanges ;) Oops! Here's one using only `InputRange` interface: I wrote my own as adjacentTuples and adjacentPairs: https://github.com/nordlow/justd/blob/master/range_ex.d#L702 Note: No yet extended to N > 2. An alternative naming would be overlappingTuples/Pairs.
Re: Adjacent Pairs Range
On Saturday, 12 September 2015 at 11:46:55 UTC, Nordlöw wrote: I wrote my own as adjacentTuples and adjacentPairs: https://github.com/nordlow/justd/blob/master/range_ex.d#L702 Note: No yet extended to N > 2. An alternative naming would be overlappingTuples/Pairs. Should this go into Phobos?
