digitalmars.D.bugs - [Issue 4124] New: toString() for BitArray and more
- d-bugmail puremagic.com (31/31) Apr 24 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4124
- d-bugmail puremagic.com (62/62) Oct 13 2011 http://d.puremagic.com/issues/show_bug.cgi?id=4124
- d-bugmail puremagic.com (19/19) Jan 25 2013 http://d.puremagic.com/issues/show_bug.cgi?id=4124
- d-bugmail puremagic.com (7/10) Jan 25 2013 http://d.puremagic.com/issues/show_bug.cgi?id=4124
- d-bugmail puremagic.com (13/13) Feb 17 2013 http://d.puremagic.com/issues/show_bug.cgi?id=4124
- d-bugmail puremagic.com (10/11) Feb 17 2013 http://d.puremagic.com/issues/show_bug.cgi?id=4124
- d-bugmail puremagic.com (8/17) Feb 17 2013 http://d.puremagic.com/issues/show_bug.cgi?id=4124
- d-bugmail puremagic.com (11/11) Jun 01 2013 http://d.puremagic.com/issues/show_bug.cgi?id=4124
- d-bugmail puremagic.com (9/9) Jun 01 2013 http://d.puremagic.com/issues/show_bug.cgi?id=4124
- d-bugmail puremagic.com (33/42) Jun 01 2013 http://d.puremagic.com/issues/show_bug.cgi?id=4124
- d-bugmail puremagic.com (11/11) Jun 02 2013 http://d.puremagic.com/issues/show_bug.cgi?id=4124
http://d.puremagic.com/issues/show_bug.cgi?id=4124
Summary: toString() for BitArray and more
Product: D
Version: future
Platform: All
OS/Version: All
Status: NEW
Severity: enhancement
Priority: P2
Component: Phobos
AssignedTo: nobody puremagic.com
ReportedBy: bearophile_hugs eml.cc
A toString() method for std.bitmanip.BitArray is useful. It can use a simple
representation like the Python bitarray:
0101001010100001
Or as java.util.BitSet (but I prefer the Python version):
{1, 3, 6, 8, 10, 15}
Other methods useful for BitArray:
- reset all bits
- set all bits
- are all bit set?
- are all bit reset?
- count set bits (there are _very_ efficient algorithms to do this).
- set n-th bit (this can be a little more efficient than bs[n]=1;)
- reset n-th bit (this can be a little more efficient than bs[n]=1;)
- flip n-th bit
I think the sort() method of BitArray is not commonly useful.
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Apr 24 2010
d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=4124
Maybe the usefulness of isSet(), set(), and reset() methods is visible with two
benchmarks. They implement the same algorithm (a simple sieve), the first uses
a BitArray, and the second a manually implemented bit array. On my 32 bit
system the second program is about two times faster than the first one.
import std.stdio, std.algorithm, std.range, std.math, std.bitmanip,
std.datetime;
uint[] primes(uint n) {
if (n < 2) return [];
BitArray F;
F.length = n + 1;
F[0] = true;
F[1] = true;
foreach (i; 2 .. cast(uint)sqrt(n))
if (!F[i])
for (uint j = i * i; j <= n; j += i)
F[j] = true;
return array(filter!((i){ return !F[i]; })(iota(n+1)));
}
void main() {
StopWatch sw;
sw.start();
primes(30_000_000);
sw.stop();
writeln(sw.peek().msecs / 1000.0);
}
import std.stdio, std.algorithm, std.range, std.math, std.datetime;
size_t[] primes(in size_t n) {
enum size_t bpc = size_t.sizeof * 8;
auto F = new size_t[n / bpc + 1];
F[] = size_t.max;
bool isSet(in size_t i) nothrow {
immutable size_t offset = i / bpc;
immutable size_t mask = 1 << (i % bpc);
return (F[offset] & mask) != 0;
}
void clear(in size_t i) nothrow {
immutable size_t offset = i / bpc;
immutable size_t mask = 1 << (i % bpc);
if ((F[offset] & mask) != 0)
F[offset] = F[offset] ^ mask;
}
clear(0);
clear(1);
foreach (i; 2 .. cast(size_t)sqrt(n))
if (isSet(i))
for (uint j = i * i; j <= n; j += i)
clear(j);
return array(filter!isSet(iota(n + 1)));
}
void main() {
StopWatch sw;
sw.start();
size_t n = primes(30_000_000).length;
sw.stop();
writeln(sw.peek().msecs / 1000.0);
writeln("n primes: ", n);
}
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Oct 13 2011
http://d.puremagic.com/issues/show_bug.cgi?id=4124
Andrej Mitrovic <andrej.mitrovich gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |andrej.mitrovich gmail.com
11:50:14 PST ---
It can use a simple
representation like the Python bitarray:
0101001010100001
What about this instead:
0101_0010_1010_0001
I think it would also be useful to be able to initialize a bitarray with an
integral literal, e.g.:
BitArray bta = bitArray!0101_0010_1010_0001;
It would statically check that all digits are 0 or 1 (is there a bit twiddling
trick for this?).
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Jan 25 2013
http://d.puremagic.com/issues/show_bug.cgi?id=4124 11:50:35 PST ---It can use a simple representation like the Python bitarray: 0101001010100001That should have been a quote. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jan 25 2013
http://d.puremagic.com/issues/show_bug.cgi?id=4124
Andrej Mitrovic <andrej.mitrovich gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |pull
AssignedTo|nobody puremagic.com |andrej.mitrovich gmail.com
17:03:02 PST ---
It would help if you didn't make multiple feature requests in a single entry.
As for toString (the name of the report), I've implemented it here:
https://github.com/D-Programming-Language/phobos/pull/1144
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Feb 17 2013
http://d.puremagic.com/issues/show_bug.cgi?id=4124It would help if you didn't make multiple feature requests in a single entry.When I am asking things like this for a single struct of Phobos: - reset all bits - set all bits Is it right to create two different enhancement requests for those two things? -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 17 2013
http://d.puremagic.com/issues/show_bug.cgi?id=4124 17:28:06 PST ---One would be enough since they're highly related. toString is largely unrelated to this though. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------It would help if you didn't make multiple feature requests in a single entry.When I am asking things like this for a single struct of Phobos: - reset all bits - set all bits Is it right to create two different enhancement requests for those two things?
Feb 17 2013
http://d.puremagic.com/issues/show_bug.cgi?id=4124 Commits pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/4f5079e4f8d38e1d469e4b28303553f36f49e33b Fixes Issue 4124 - Implement toString for BitArray. https://github.com/D-Programming-Language/phobos/commit/9d331e2dc43a590c486c1b4862c0b1173b2f6799 Issue 4124 - Implement toString for BitArray. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 01 2013
http://d.puremagic.com/issues/show_bug.cgi?id=4124
Kenji Hara <k.hara.pg gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
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Jun 01 2013
http://d.puremagic.com/issues/show_bug.cgi?id=4124Commits pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/4f5079e4f8d38e1d469e4b28303553f36f49e33b Fixes Issue 4124 - Implement toString for BitArray. https://github.com/D-Programming-Language/phobos/commit/9d331e2dc43a590c486c1b4862c0b1173b2f6799 Issue 4124 - Implement toString for BitArray.Thank you. This introduces a good toString for BitArray. Then I will move elsewhere the missing things. I think this stuff can go in a single enhancement request because they are easy and short to implement: - reset all bits - set all bits - are all bit set? - are all bit reset? - set n-th bit (this can be a little more efficient than bs[n]=1;) - reset n-th bit (this can be a little more efficient than bs[n]=1;) - flip n-th bit Maybe it's better to move this into a separated ER because it looks simple but implementing a pop count very efficiently is not so easy: - count set bits ---------------- Now (unlike "%s") "%b" produces a string output that's not usable to build a new BitArray, maybe this is another worth enhancement request: import std.stdio, std.bitmanip, std.conv, std.string; void main() { BitArray b1; b1.init([0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1]); writefln("%b", b1); // Prints: 00001111_00001111 BitArray b2; // Error: function std.bitmanip.BitArray.init (bool[] ba) // is not callable using argument types (string) b2.init("00001111_00001111"); } -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 01 2013
http://d.puremagic.com/issues/show_bug.cgi?id=4124
bearophile_hugs eml.cc changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|toString() for BitArray and |toString() for BitArray
|more |
Removed "and more" from the title
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Jun 02 2013