Re: Generating Strings with Random Contents
On Wednesday, 16 July 2014 at 23:24:24 UTC, Joseph Rushton
Wakeling via Digitalmars-d-learn wrote:
Are you interested in having each character in the sequence
randomly chosen independently of all the others, or do you want
a random subset of all available characters (i.e. no character
appears more than once), or something else again?
Just a random dchar (ciode point) sample like this:
/** Generate Random Contents of $(D x).
See also:
http://forum.dlang.org/thread/emlgflxpgecxsqwea...@forum.dlang.org
*/
auto ref randInPlace(ref dchar x) @trusted
{
auto ui = uniform(0,
0xD800 +
(0x11 - 0xE000) - 2 // minus two for
U+FFFE and U+
);
if (ui 0xD800)
{
return x = ui;
}
else
{
ui -= 0xD800;
ui += 0xE000;
// skip undefined
if (ui 0xFFFE)
return x = ui;
else
ui += 2;
assert(ui 0x11);
return x = ui;
}
}
I don't know how well this plays with
unittest
{
import dbg;
dln(randomized!dchar);
dstring d =
alphaalphaalphaalphaalphaalphaalphaalphaalphaalpha;
dln(d.randomize);
}
though.
See complete logic at
https://github.com/nordlow/justd/blob/master/random_ex.d
Re: Generating Strings with Random Contents
Alternative: randomSample(lowercase, 10, lowercase.length).writeln; No, I don't think that's appropriate, because it will pick 10 individual characters from a, b, c, ... , z (i.e. no character will appear more than once), and the characters picked will appear in alphabetical order. Incidentally, if lowercase has the .length property, there's no need to pass the length separately to randomSample. Just passing lowercase itself and the number of sample points desired is sufficient.
Re: Generating Strings with Random Contents
Nordlöw: Could someone elaborate shortly which cases this means? All cases where you really can't live without it :-) It's like a cast(. Bye, bearophile
Re: Generating Strings with Random Contents
On Tuesday, 15 July 2014 at 00:03:04 UTC, bearophile wrote: to avoid using @trusted in most cases. Could someone elaborate shortly which cases this means?
Re: Generating Strings with Random Contents
On Tuesday, 15 July 2014 at 18:50:06 UTC, bearophile wrote: All cases where you really can't live without it :-) It's like Hmm. I guess I'm gonna have to remove some @trusted tagging then ;)
Generating Strings with Random Contents
Is there a natural way of generating/filling a string/wstring/dstring of a specific length with random contents?
Re: Generating Strings with Random Contents
Nordlöw:
Is there a natural way of generating/filling a
string/wstring/dstring of a specific length with random
contents?
Do you mean something like this?
import std.stdio, std.random, std.ascii, std.range, std.conv;
string genRandomString(in size_t len) {
return len
.iota
.map!(_ = lowercase[uniform(0, $)])
.text;
}
void main() {
import std.stdio;
10.genRandomString.writeln;
}
Bye,
bearophile
Re: Generating Strings with Random Contents
On Monday, 14 July 2014 at 22:21:36 UTC, bearophile wrote:
Nordlöw:
Is there a natural way of generating/filling a
string/wstring/dstring of a specific length with random
contents?
Do you mean something like this?
import std.stdio, std.random, std.ascii, std.range, std.conv;
string genRandomString(in size_t len) {
return len
.iota
.map!(_ = lowercase[uniform(0, $)])
.text;
}
void main() {
import std.stdio;
10.genRandomString.writeln;
}
Bye,
bearophile
Alternative:
randomSample(lowercase, 10, lowercase.length).writeln;
Re: Generating Strings with Random Contents
On Monday, 14 July 2014 at 22:27:57 UTC, Brad Anderson wrote: Alternative: randomSample(lowercase, 10, lowercase.length).writeln; std.ascii should really be using std.encoding.AsciiString. Then that length wouldn't be necessary.
Re: Generating Strings with Random Contents
Brad Anderson: Alternative: randomSample(lowercase, 10, lowercase.length).writeln; From randomSample docs: Selects a random subsample out of r, containing exactly n elements. The order of elements is the same as in the original range. Bye, bearophile
Re: Generating Strings with Random Contents
On Monday, 14 July 2014 at 22:21:36 UTC, bearophile wrote:
Nordlöw:
Is there a natural way of generating/filling a
string/wstring/dstring of a specific length with random
contents?
Do you mean something like this?
import std.stdio, std.random, std.ascii, std.range, std.conv;
string genRandomString(in size_t len) {
return len
.iota
.map!(_ = lowercase[uniform(0, $)])
.text;
}
void main() {
import std.stdio;
10.genRandomString.writeln;
}
Bye,
bearophile
I was specifically interested in something that exercises (random
samples) potentially _all_ code points for string, wstring and
dstring (all code units that is).
Re: Generating Strings with Random Contents
Nordlöw: I was specifically interested in something that exercises (random samples) potentially _all_ code points for string, wstring and dstring (all code units that is). That's harder. Generating all uints and then testing if it's a Unicode dchar seems possible. Bye, bearophile
Re: Generating Strings with Random Contents
On Monday, 14 July 2014 at 22:35:59 UTC, Nordlöw wrote: On Monday, 14 July 2014 at 22:32:51 UTC, Nordlöw wrote: I believe defining a complete random sampling of all code units in dchar is a good start right? This can then be reused to lazily convert while filling in a string and wstring. isValidCodePoint() at http://dlang.org/phobos/std_encoding.html might be were to start.
Re: Generating Strings with Random Contents
On Monday, 14 July 2014 at 22:32:51 UTC, Nordlöw wrote: I believe defining a complete random sampling of all code units in dchar is a good start right? This can then be reused to lazily convert while filling in a string and wstring.
Re: Generating Strings with Random Contents
Nordlöw: I believe defining a complete random sampling of all code units in dchar is a good start right? This can then be reused to lazily convert while filling in a string and wstring. Several combinations of unicode chars are not meaningful/valid (like pairs of ligatures). Any thing that has to work correctly with Unicode is complex. Bye, bearophile
Re: Generating Strings with Random Contents
On Monday, 14 July 2014 at 22:39:08 UTC, Nordlöw wrote:
might be were to start.
Is it really this simple?
bool isValidCodePoint(dchar c)
{
return c 0xD800 || (c = 0xE000 c 0x11);
}
Re: Generating Strings with Random Contents
On Monday, 14 July 2014 at 22:39:15 UTC, bearophile wrote: Several combinations of unicode chars are not meaningful/valid (like pairs of ligatures). Any thing that has to work correctly with Unicode is complex. So I guess we need something more than just isValidCodePoint right?
Re: Generating Strings with Random Contents
On Monday, 14 July 2014 at 22:32:25 UTC, bearophile wrote: Brad Anderson: Alternative: randomSample(lowercase, 10, lowercase.length).writeln; From randomSample docs: Selects a random subsample out of r, containing exactly n elements. The order of elements is the same as in the original range. Bye, bearophile Hmm, good catch. Not the behavior I expected.
Re: Generating Strings with Random Contents
On Monday, 14 July 2014 at 22:45:29 UTC, Nordlöw wrote: So I guess we need something more than just isValidCodePoint right? Here's a first try: https://github.com/nordlow/justd/blob/master/random_ex.d#L53
Re: Generating Strings with Random Contents
Nordlöw: https://github.com/nordlow/justd/blob/master/random_ex.d#L53 Isn't @trusted mostly for small parts of Phobos code? I suggest to avoid using @trusted in most cases. Bye, bearophile
