On Monday, 30 January 2017 at 12:31:33 UTC, albert-j wrote:
OK, got it. Can you do removal without reallocation with
std.container.array?
Array!int arr;
foreach (i; 0..10) arr ~= i;
Sorry, sent too early.
arr = arr[].remove!(x=> x > 5); //Doesn't work withouth
calling
On Monday, 30 January 2017 at 10:45:03 UTC, cym13 wrote:
Meh.
Forget that, bad memory. remove isn't working in-place. However
slapping ".array" is still asking explicitely for reallocation,
so just forget it. Here is a code that works:
import std.conv;
import std.stdio;
import std.format;
On Monday, 30 January 2017 at 00:17:51 UTC, ag0aep6g wrote:
Removing works by overwriting the array with only the wanted
values and discarding the rest.
But then why do I get this:
import std.stdio, std.algorithm, std.array;
int[] arr;
foreach (i; 0..10) arr ~= i; // [0, 1, 2,
On Monday, 30 January 2017 at 00:17:51 UTC, ag0aep6g wrote:
[...]
Great explanation, thank you!
On Sunday, 29 January 2017 at 23:48:40 UTC, Jordan Wilson wrote:
You need to do something like this:
auto arrMap = arr.filter!(x => x > 5).map!(x => x^^2).array;
It's because arrMap is lazy evaluated.
So does it mean that I cannot assign FilterResult and MapResult
to a variable and safely
On Saturday, 28 January 2017 at 11:54:58 UTC, cym13 wrote:
I am trying to wrap my head around lazy evaluation during
filtering/mapping, but there's something I don't understand.
I want to create an array, square some elements, remove some
elements from original array and add the squared
On Friday, 27 January 2017 at 08:15:56 UTC, Dukc wrote:
void main()
{ import std.stdio, std.algorithm, std.range, std.array,
std.datetime;
int[] a = [1, 2, 3, 4, 5, 6, 7, 4].cycle.take(2000).array;
int[] b = [3, 4, 6].cycle.take(2000).array;
void originalMethod()
{ auto c
On Friday, 27 January 2017 at 08:15:56 UTC, Dukc wrote:
TickDuration(28085)
TickDuration(42868)
TickDuration(1509)
Thank you, this is very helpful. I am also wondering why the
standard library doesn't have convenience functions for this,
e.g. like Java's removeAll? Now there's more typing
On Thursday, 26 January 2017 at 13:21:38 UTC, Dukc wrote:
import std.stdio, std.algorithm, std.range, std.array;
int[] a = [1, 2, 3, 4, 5, 6, 7, 4];
int[] b = [3, 4, 6];
auto sortedB = sort(b.dup);
auto c = a
. filter!(i => !sortedB.contains(i))
. array
;
assert(c == [1, 2, 5, 7]);
If
What is the D idiom for removing array elements that are present
in another array?
Is this the right/fastest way?
int[] a = [1, 2, 3, 4, 5, 6, 7, 4];
int[] b = [3, 4, 6];
auto c = a.remove!(x => b.canFind(x));
assert(c == [1, 2, 5, 7]);
Without seeing the source there is nothing we can do.
Usually performant d-code looks quite diffrent from java code.
For example to avoid the gc :)
Well it is actually ODE solver from Numerical recipes (originally
in C++) that I am trying to do in D. Code translation seems very
I have translated some simulation code from Java into D (a few
classes, mostly manipulation of double arrays in small methods).
D version runs 10-30% slower than Java (ldc2, dub release build).
Profiling did not show any obvious bottlenecks. I am wondering
whether I missed something, or such
I'm not sure if it's what happening in this case but, in code
as simple as this, function calls can sometimes be the
bottleneck. You should see how compiling with/without -O
affects performance, and adding `pragma(inline)` to funcB.
I guess my question is whether it is possible to have
In anycase, what is the correct notation for indexing?
x = new int[][](width, height)
and x[height][width] or x[width][height]?
It's x[width][height], but because indexing is 0-based, largest
valid indexes are
x[width-1][height-1].
I'm not sure if it's what happening in this case but, in code
as simple as this, function calls can sometimes be the
bottleneck. You should see how compiling with/without -O
affects performance, and adding `pragma(inline)` to funcB.
When compiled with -inline, the profiler does not report the
Let's say I want to create an array of random numbers and do some
operations on them:
void main() {
import std.random;
//Generate array of random numbers
int arrSize = 1;
double[] arr = new double[](arrSize);
foreach (i; 0..arrSize)
arr[i] = uniform01();
Thank you for all your answers. I was concerned because I'm
dealing with a small function that is called many times and where
the bulk of the calculations in the simulation takes place. So
even 5% performance difference would be significant for me. But
it is good to know that compilers are
Is it possible to refer to an array element by a descriptive
name, just for code clarity, without performance overhead? E.g.
void aFunction(double[] arr) {
double importantElement = arr[3];
... use importantElement ...
}
But the above, I suppose, introduces an extra copy operation?
Have you seen https://github.com/economicmodeling/containers it
has a HashSet
http://economicmodeling.github.io/containers/containers/hashset.HashSet.html
Just curious, how is it different from Tango's implementation?
Try an older version.
Before resorting to that, I am also trying to "dub build
--compiler=gdc". Getting different types of errors:
../../../.dub/packages/tango-1.0.3_2.068/tango/tango/math/IEEE.d:614:17: error:
instead of C-style syntax, use D-style syntax 'real[3][] vals' [-Werror]
I thought Tango was obsolete a long time ago.
Is there a specific reason you need to use Tango and can't use
Phobos?
I need a Set implementation and from what I understand there
isn't one in Phobos right now?
Since I just do "dub build", I assume it invokes dmd? I have
v2.072.0.
I am trying to use Tango in a dub project because I need a
HashSet. I added Tango as a dependency to the dub.json, but now
dub gives me a bunch of depreciation warnings and a few errors,
like
../../../.dub/packages/tango-1.0.3_2.068/tango/tango/util/log/Log.d(349,51):
Error: undefined
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