On Saturday, 22 January 2022 at 01:33:16 UTC, Steven
Schveighoffer wrote:
That second `valuesPerRecord` is not used in the lambda, and
also it's not referring to the original element, it's the name
of a parameter in the lambda.
Are you sure this is doing what you want?
-Steve
It just
On Saturday, 22 January 2022 at 01:33:16 UTC, Steven
Schveighoffer wrote:
so I why watching this video by Andrei:
https://www.youtube.com/watch?v=mCrVYYlFTrA
In it, he talked about writing the simplest design that could
possibly work
Which got me thinking
//
module test;
On 1/21/22 6:24 PM, forkit wrote:
On Friday, 21 January 2022 at 22:25:32 UTC, forkit wrote:
I really like how alias and mixin can simplify my code even further:
//---
int[][int][] CreateDataSet
(const(int) recordsNeeded, const(int) valuesPerRecord)
{
int[][int][] records;
On Friday, 21 January 2022 at 22:25:32 UTC, forkit wrote:
I really like how alias and mixin can simplify my code even
further:
//---
int[][int][] CreateDataSet
(const(int) recordsNeeded, const(int) valuesPerRecord)
{
int[][int][] records;
records.reserve(recordsNeeded);
const
On Friday, 21 January 2022 at 21:56:33 UTC, H. S. Teoh wrote:
What's the point of calling .dup here? The only reference to
records is going out of scope, so why can't you just return it?
The .dup is just creating extra work for nothing.
T
good pickup. thanks ;-)
//
module test;
On Fri, Jan 21, 2022 at 09:43:38PM +, forkit via Digitalmars-d-learn wrote:
> On Friday, 21 January 2022 at 21:01:11 UTC, forkit wrote:
[...]
> even better, I got rid of all those uncessary arrays ;-)
>
> // ---
>
> int[][int][] CreateDataSet
> (const(int) recordsNeeded,
On Friday, 21 January 2022 at 21:43:38 UTC, forkit wrote:
oops... should be:
// ---
int[][int][] CreateDataSet
(const(int) recordsNeeded, const(int)valuesPerRecord)
{
int[][int][] records;
records.reserve(recordsNeeded);
const int iotaStartNum = 100_000_001;
foreach(i, id;
On Friday, 21 January 2022 at 21:01:11 UTC, forkit wrote:
even better, I got rid of all those uncessary arrays ;-)
// ---
int[][int][] CreateDataSet
(const(int) recordsNeeded, const(int)valuesPerRecord)
{
int[][int][] records;
records.reserve(recordsNeeded);
foreach(i, id;
On Friday, 21 January 2022 at 18:50:46 UTC, Steven Schveighoffer
wrote:
Yeah, iota is a random-access range, so you can just pass it
directly, and not allocate anything.
Looking at the usage, it doesn't need to be an array at all.
But modifying the code to properly accept the range might
On Friday, 21 January 2022 at 18:36:42 UTC, H. S. Teoh wrote:
This is wasteful if you're not planning to use every ID in this
million-entry long array. Much better to just use an AA to
keep track of which IDs have already been generated instead.
Of course, if you plan to use most of the
On 1/21/22 1:36 PM, H. S. Teoh wrote:
On Fri, Jan 21, 2022 at 10:12:42AM +, forkit via Digitalmars-d-learn wrote:
[...]
// id needs to be 9 digits, and needs to start with 999
int[] idArray = takeExactly(iota(999*10^^6, 10^^9),
recordsNeeded).array;
[...]
This is wasteful if
On Fri, Jan 21, 2022 at 10:12:42AM +, forkit via Digitalmars-d-learn wrote:
[...]
> Random rnd;
> static this() { rnd = Random(unpredictableSeed); } // thanks Ali
Actually you don't even need to do this, unless you want precise control
over the initialization of your RNG. If you don't
On Fri, Jan 21, 2022 at 09:10:56AM +, forkit via Digitalmars-d-learn wrote:
[...]
> turns out the problem has nothing to do with appender...
>
> It's actually this line:
>
> if (!idArray.canFind(x)):
>
> when i comment this out in the function below, the program does what I
> want in
On Friday, 21 January 2022 at 09:10:56 UTC, forkit wrote:
ok... in the interest of corecting the code I posted previously...
... here is a version that actually works in secs (for a million
records), as opposed to hours!
// ---
/+
On Friday, 21 January 2022 at 08:53:26 UTC, Stanislav Blinov
wrote:
turns out the problem has nothing to do with appender...
It's actually this line:
if (!idArray.canFind(x)):
when i comment this out in the function below, the program does
what I want in seconds.
only problem is, the
On Friday, 21 January 2022 at 03:50:37 UTC, forkit wrote:
I might have to use a kindof stringbuilder instead, then write
a massive string once to the file.
You're using writeln, which goes through C I/O buffered writes.
Whether you make one call or several is of little consequence -
you're
On Friday, 21 January 2022 at 04:08:33 UTC, forkit wrote:
// --
void ProcessRecords
(in int[][int][] recArray, const(string) fname)
{
auto file = File(fname, "w");
scope(exit) file.close;
Appender!string bigString = appender!string;
bigString.reserve(recArray.length);
On Friday, 21 January 2022 at 03:57:01 UTC, H. S. Teoh wrote:
std.array.appender is your friend.
T
:-)
// --
void ProcessRecords
(in int[][int][] recArray, const(string) fname)
{
auto file = File(fname, "w");
scope(exit) file.close;
Appender!string bigString = appender!string;
On Fri, Jan 21, 2022 at 03:50:37AM +, forkit via Digitalmars-d-learn wrote:
[...]
> I might have to use a kindof stringbuilder instead, then write a
> massive string once to the file.
[...]
std.array.appender is your friend.
T
--
Meat: euphemism for dead animal. -- Flora
On Friday, 21 January 2022 at 03:45:08 UTC, forkit wrote:
On Friday, 21 January 2022 at 02:30:35 UTC, Ali Çehreli wrote:
The bigger question is, why did 'formattedRecords' exist at
all? You could have written the output directly to the file.
Oh. this was intentional, as I wanted to write
On Friday, 21 January 2022 at 02:30:35 UTC, Ali Çehreli wrote:
The bigger question is, why did 'formattedRecords' exist at
all? You could have written the output directly to the file.
Oh. this was intentional, as I wanted to write once, and only
once, to the file.
The consequence of that
On 1/20/22 17:35, forkit wrote:
> module test;
> @safe
Does that make just the following definition @safe or the entire module
@safe? Trying... Yes, I am right. To make the module safe, use the
following syntax:
@safe:
> idArray.reserve(recordsNeeded);
[...]
> idArray ~=
On Friday, 21 January 2022 at 01:35:40 UTC, forkit wrote:
oops. nasty mistake to make ;-)
module test;
@safe
should be:
module test;
@safe:
On Thursday, 20 January 2022 at 23:49:59 UTC, Ali Çehreli wrote:
so here is final code, in idiomatic D, as far as I can tell ;-)
curious output when using -profile=gc
.. a line referring to:
std.array.Appender!(immutable(char)[]).Appender.Data
std.array.Appender!string.Appender.this
On 1/20/22 6:01 PM, forkit wrote:
On Thursday, 20 January 2022 at 22:31:17 UTC, Steven Schveighoffer wrote:
Because it would allow altering const data.
I'm not sure I understand. At what point in this function is valuesArray
modified, and thus preventing it being passed in with const?
On 1/20/22 15:10, Ali Çehreli wrote:
> void foo(const int[]) {} // Idiomatic
As H. S. Teoh would add at this point, that is not idiomatic but the
following are (with different meanings):
void foo(const(int)[]) {} // Idiomatic
void foo(const(int[])) {} // Idiomatic
> void
On 1/20/22 15:01, forkit wrote:
> On Thursday, 20 January 2022 at 22:31:17 UTC, Steven Schveighoffer wrote:
>>
>> Because it would allow altering const data.
>>
>
> I'm not sure I understand. At what point in this function is valuesArray
> modified, and thus preventing it being passed in with
On Thursday, 20 January 2022 at 22:31:17 UTC, Steven
Schveighoffer wrote:
Because it would allow altering const data.
I'm not sure I understand. At what point in this function is
valuesArray modified, and thus preventing it being passed in with
const?
// ---
int[][int][] CreateDataSet
On 1/20/22 5:07 PM, forkit wrote:
On Thursday, 20 January 2022 at 21:16:46 UTC, forkit wrote:
Cannot work out why I cannot pass valuesArray in as ref const??
get error: Error: cannot append type `const(int[])[const(int)]` to type
`int[][int][]`
Because it would allow altering const data.
On Thursday, 20 January 2022 at 21:16:46 UTC, forkit wrote:
Cannot work out why I cannot pass valuesArray in as ref const??
get error: Error: cannot append type `const(int[])[const(int)]`
to type `int[][int][]`
// --
int[][int][] CreateDataSet(ref const int[] idArray, ref
On Thursday, 20 January 2022 at 12:40:09 UTC, Stanislav Blinov
wrote:
Allocating 4 megs to generate 10 numbers??? You can generate a
random number between 99900 and 10.
...
// id needs to be 9 digits, and needs to start with 999
x = uniform(999*10^^6, 10^^9);
On Thursday, 20 January 2022 at 12:15:56 UTC, forkit wrote:
void createUniqueIDArray(ref int[] idArray, int recordsNeeded)
{
idArray.reserve(recordsNeeded);
debug { writefln("idArray.capacity is %s",
idArray.capacity); }
// id needs to be 9 digits, and needs to start with 999
On Thursday, 20 January 2022 at 10:11:10 UTC, bauss wrote:
Don't make them random then, but use an incrementor.
If you can have ids that aren't integers then you could use
uuids too.
https://dlang.org/phobos/std_uuid.html
The 'uniqueness' of id would actually be created in the database.
On Thursday, 20 January 2022 at 04:00:59 UTC, forkit wrote:
On Thursday, 20 January 2022 at 00:30:44 UTC, H. S. Teoh wrote:
Do the id's have to be unique?
yep...
Don't make them random then, but use an incrementor.
If you can have ids that aren't integers then you could use uuids
too.
On Thursday, 20 January 2022 at 04:38:39 UTC, forkit wrote:
all done ;-)
// ---
module test;
import std.stdio : writeln;
import std.range : iota, isForwardRange, hasSlicing, hasLength,
isInfinite;
import std.array : array, Appender;
import std.random : Random, unpredictableSeed, dice,
On Thursday, 20 January 2022 at 04:00:59 UTC, forkit wrote:
void makeUniqueIDs(ref uint[] arr, size_t sz)
{
...
}
arrg!
what was i thinking! ;-)
// ---
void makeUniqueIDs(ref uint[] arr, size_t sz)
{
arr.reserve(sz);
// id needs to be 9 digits, and needs to start with 999
On Thursday, 20 January 2022 at 00:30:44 UTC, H. S. Teoh wrote:
Do the id's have to be unique?
yep...
I'm almost there ;-)
// ---
module test;
import std.stdio : writeln;
import std.range : iota, isForwardRange, hasSlicing, hasLength,
isInfinite;
import std.array : array, Appender;
On Thu, Jan 20, 2022 at 12:12:56AM +, forkit via Digitalmars-d-learn wrote:
[...]
> createBoolAssociativeMatrix(mArrBool,3, 2);
>
> [ [1000:[1, 0]], [1001:[1, 1]], [1001:[1, 0]]]
>
>
> where 1000 is some random id...
Do the id's have to be unique? If not, std.random.uniform() would do
the
On Wednesday, 19 January 2022 at 21:59:15 UTC, forkit wrote:
so at the moment i can get a set number of tuples, with a set
number of bool values contained within each tuple.
e.g.
createBoolMatrix(mArrBool,3, 2);
[[1, 0], [1, 1], [1, 0]]
my next challenge (more for myself, but happy for
On 1/19/22 15:21, H. S. Teoh wrote:
> On Wed, Jan 19, 2022 at 02:33:02PM -0800, Ali Çehreli via
Digitalmars-d-learn wrote:
> [...]
>> // Returning a dynamically allocated array looks expensive
>> // here. Why not use a struct or std.typecons.Tuple instead?
>
> Premature optimization. ;-)
Not
On Wednesday, 19 January 2022 at 22:35:58 UTC, Ali Çehreli wrote:
so I combined ideas from all responses:
// --
module test;
import std.stdio : writeln;
import std.range : iota, isForwardRange, hasSlicing, hasLength,
isInfinite, array;
import std.random : Random, unpredictableSeed, dice;
On Wednesday, 19 January 2022 at 23:22:17 UTC, forkit wrote:
oops
// e.g: create a matrix consisting of 5 tuples, with each tuple
containing 3 random bools (0 or 1)
createBoolMatrix(mArrBool,5, 3);
On Wed, Jan 19, 2022 at 02:33:02PM -0800, Ali Çehreli via Digitalmars-d-learn
wrote:
[...]
> // Returning a dynamically allocated array looks expensive
> // here. Why not use a struct or std.typecons.Tuple instead?
Premature optimization. ;-) There's nothing wrong with allocating an
array.
If
On 1/19/22 14:33, Ali Çehreli wrote:
> Random rnd;
>
> shared static this() {
>rnd = Random(unpredictableSeed);
> }
But that's a mistake: If rnd is thread-local like that, it should be
initialized in a 'static this' (not 'shared static this'). Otherwise,
only the main thread's 'rnd' would
On 1/19/22 13:59, forkit wrote:
> void createBoolMatrix(ref uint[][] m)
> {
> auto rnd = Random(unpredictableSeed);
That works but would be unnecessarily slow and be against the idea of
random number generators. The usual approach is, once you have a
randomized sequence, you just
On Wed, Jan 19, 2022 at 09:59:15PM +, forkit via Digitalmars-d-learn wrote:
> so I have this code below, that creates an array of tuples.
>
> but instead of hardcoding 5 tuples (or hardcoding any amount of
> tuples), what I really want to do is automate the creation of
> how-ever-many tuples
On Wednesday, 19 January 2022 at 21:59:15 UTC, forkit wrote:
oh. that randomShuffle was unnecessary ;-)
so I have this code below, that creates an array of tuples.
but instead of hardcoding 5 tuples (or hardcoding any amount of
tuples),
what I really want to do is automate the creation of
how-ever-many tuples I ask for:
i.e.
instead of calling this: createBoolMatrix(mArrBool);
I would call
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