this one is even faster than c++:
http://ideone.com/TRDsOo
On Sun, Aug 13, 2017 at 10:00 AM, Daniel Kozak <kozz...@gmail.com> wrote:
> my second version on ldc takes 380ms and c++ version on same compiler
> (clang), takes 350ms, so it seems to be almost same
>
> On Sun, Aug 13, 2017 at 9:51 AM, amfvcg via Digitalmars-d-learn <
> digitalmars-d-learn@puremagic.com> wrote:
>
>> On Sunday, 13 August 2017 at 07:30:32 UTC, Daniel Kozak wrote:
>>
>>> Here is more D idiomatic way:
>>>
>>> import std.stdio : writeln;
>>> import std.algorithm.comparison: min;
>>> import std.algorithm.iteration: sum;
>>> import core.time: MonoTime, Duration;
>>>
>>>
>>> auto sum_subranges(T)(T input, uint range)
>>> {
>>> import std.array : array;
>>> import std.range : chunks, ElementType;
>>> import std.algorithm : map;
>>>
>>> if (range == 0)
>>> {
>>> return ElementType!(T)[].init;
>>> }
>>> return input.chunks(range).map!(sum).array;
>>> }
>>>
>>> unittest
>>> {
>>> assert(sum_subranges([1,1,1], 2) == [2, 1]);
>>> assert(sum_subranges([1,1,1,2,3,3], 2) == [2, 3, 6]);
>>> assert(sum_subranges([], 2) == []);
>>> assert(sum_subranges([1], 2) == [1]);
>>> assert(sum_subranges([1], 0) == []);
>>> }
>>>
>>>
>>> int main()
>>> {
>>> import std.range : iota, array;
>>> auto v = iota(0,1000000);
>>> int sum;
>>> MonoTime beg = MonoTime.currTime;
>>> for (int i=0; i < 100; i++)
>>> sum += cast(int)sum_subranges(v,2).length;
>>> MonoTime end = MonoTime.currTime;
>>> writeln(end-beg);
>>> writeln(sum);
>>> return sum;
>>> }
>>>
>>> On Sun, Aug 13, 2017 at 9:13 AM, Daniel Kozak <kozz...@gmail.com> wrote:
>>>
>>> this works ok for me with ldc compiler, gdc does not work on my arch
>>>> machine so I can not do comparsion to your c++ versin (clang does not work
>>>> with your c++ code)
>>>>
>>>> import std.stdio : writeln;
>>>> import std.algorithm.comparison: min;
>>>> import std.algorithm.iteration: sum;
>>>> import core.time: MonoTime, Duration;
>>>>
>>>>
>>>> T[] sum_subranges(T)(T[] input, uint range)
>>>> {
>>>> import std.array : appender;
>>>> auto app = appender!(T[])();
>>>> if (range == 0)
>>>> {
>>>> return app.data;
>>>> }
>>>> for (uint i; i < input.length; i=min(i+range, input.length))
>>>> {
>>>> app.put(sum(input[i..min(i+range, input.length)]));
>>>> }
>>>> return app.data;
>>>> }
>>>>
>>>> unittest
>>>> {
>>>> assert(sum_subranges([1,1,1], 2) == [2, 1]);
>>>> assert(sum_subranges([1,1,1,2,3,3], 2) == [2, 3, 6]);
>>>> assert(sum_subranges([], 2) == []);
>>>> assert(sum_subranges([1], 2) == [1]);
>>>> assert(sum_subranges([1], 0) == []);
>>>> }
>>>>
>>>>
>>>> int main()
>>>> {
>>>> import std.range : iota, array;
>>>> auto v = iota(0,1000000).array;
>>>> int sum;
>>>> MonoTime beg = MonoTime.currTime;
>>>> for (int i=0; i < 100; i++)
>>>> sum += cast(int)sum_subranges(v,2).length;
>>>> MonoTime end = MonoTime.currTime;
>>>> writeln(end-beg);
>>>> writeln(sum);
>>>> return sum;
>>>> }
>>>>
>>>> On Sun, Aug 13, 2017 at 9:03 AM, Neia Neutuladh via Digitalmars-d-learn
>>>> < digitalmars-d-learn@puremagic.com> wrote:
>>>>
>>>> [...]
>>>>>
>>>>
>> Thank you all for the replies. Good to know the community is alive in d :)
>>
>> Let's settle the playground:
>> D : http://ideone.com/h4fnsD
>> C++: http://ideone.com/X1pyXG
>>
>> Both using GCC under the hood.
>> C++ in 112 ms;
>> D in :
>> - 2.5 sec with original source;
>> - 2.5 sec with Daniel's 1st version;
>> - 5 sec timeout exceeded with Daniel's 2nd version;
>> - 1.8 sec with Neia-like preallocation;
>>
>> So still it's not that neaty.
>>
>> (What's interesting C++ code generates 2KLOC of assembly, and Dlang @ ldc
>> 12KLOC - checked at godbolt).
>>
>> P.S. For C++ version to work under clang, the function which takes
>> (BinaryOp) must go before the other one (my bad).
>>
>
>
