Re: array to string functional?
On Friday, 14 September 2018 at 20:43:45 UTC, SrMordred wrote:
On Friday, 14 September 2018 at 19:44:37 UTC, berni wrote:
a) I've got an int[] which contains only 0 und 1. And I want
to end with a string, containing 0 and 1. So [1,1,0,1,0,1]
should become "110101". Of course I can do this with a loop
and ~. But I think it should be doable with functional style,
which is something I would like to understand better. Can
anyone help me here? (I think a.map!(a=>to!char(a+'0')) does
the trick, but is this good style or is there a better way?)
Yes, that's fine. That gives you a range; if you want an array,
call array() with that expression. Also, since you know the
addition won't overflow, you can substitute the to!char call with
a cast (arr.map!(c => cast(char)(c + '0')).array).
Another option is to index a string literal: arr.map!(c =>
"01"[c]).array
auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
a.map!(to!string)
.join("")
.chunks(4)
.map!(to!string) //don´t know why the chunks are not
already strings at this point ;/
.writeln;
That's needlessly complicated and inefficient; this will allocate
one string per array element.
If you don't need the result to be actual arrays, this works:
auto res = [1,0,1,1,1,0,1,0,1,1,1,1,0]
.map!(c => "01"[c])
.chunks(4);
assert(equal!equal(res, ["1011","1010","","0"]));
If you need a real array of arrays:
auto arr = res
.map!array
.array;
assert(arr == ["1011","1010","","0"]);
Re: array to string functional?
Can you post a complete, runnable example that illustrates your problem? Strange as it is, now it works here too... - I don't know, what went wrong yesterday. Thanks anyway. :-)
Re: array to string functional?
On Saturday, 15 September 2018 at 20:04:36 UTC, berni wrote:
Anotherone I'm not getting to work: From some output with
newlines I want to discard all lines, that start with a # and
select part of the other lines with a regex. (I know the regex
r".*" is quite useless, but it will be replaced by something
more usefull.)
I tried the following, but non worked:
output.split("\n").filter!(a=>a.length>0 &&
a[0]!='#').matchFirst(r".*");
output.split("\n").filter!(a=>a.length>0 &&
a[0]!='#').array.matchFirst(r".*");
output.split("\n").filter!(a=>a.length>0 &&
a[0]!='#').array.map!(matchFirst(r".*"));
output.split("\n").filter!(a=>a.length>0 &&
a[0]!='#').array.map!(a=>matchFirst(a,r".*"));
Any ideas?
Your last example works for me: https://run.dlang.io/is/F5n3mk
Can you post a complete, runnable example that illustrates your
problem?
Re: array to string functional?
Anotherone I'm not getting to work: From some output with
newlines I want to discard all lines, that start with a # and
select part of the other lines with a regex. (I know the regex
r".*" is quite useless, but it will be replaced by something more
usefull.)
I tried the following, but non worked:
output.split("\n").filter!(a=>a.length>0 &&
a[0]!='#').matchFirst(r".*");
output.split("\n").filter!(a=>a.length>0 &&
a[0]!='#').array.matchFirst(r".*");
output.split("\n").filter!(a=>a.length>0 &&
a[0]!='#').array.map!(matchFirst(r".*"));
output.split("\n").filter!(a=>a.length>0 &&
a[0]!='#').array.map!(a=>matchFirst(a,r".*"));
Any ideas?
Re: array to string functional?
On Saturday, 15 September 2018 at 05:39:48 UTC, berni wrote: Oh, thanks. What I didn't know about was join. Now I wonder how I could have found out about it, without asking here? Even yet I know it's name I cannot find it, nighter in the language documentation nor in the library documentation. Probably the easiest way to find something in the documentation is to use the unofficial mirror at http://dpldocs.info/. Type "join" into the search box there, and you'll get `std.array.join` (the function I used) as the first result.
Re: array to string functional?
On Saturday, 15 September 2018 at 06:16:59 UTC, bauss wrote:
On Friday, 14 September 2018 at 20:43:45 UTC, SrMordred wrote:
What you want is std.range.chunks
auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
a.map!(to!string)
.join("")
.chunks(4)
.map!(to!string) //don´t know why the chunks are not
already strings at this point ;/
.writeln;
They're not strings, because they're now 4 ranges of integers.
Then you map each of those 4 integer ranges into 4 strings.
Oh wait I didn't see your first map!(to!string)
I take back what I just said.
Re: array to string functional?
On Friday, 14 September 2018 at 20:43:45 UTC, SrMordred wrote:
What you want is std.range.chunks
auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
a.map!(to!string)
.join("")
.chunks(4)
.map!(to!string) //don´t know why the chunks are not
already strings at this point ;/
.writeln;
They're not strings, because they're now 4 ranges of integers.
Then you map each of those 4 integer ranges into 4 strings.
Re: array to string functional?
On Friday, September 14, 2018 11:39:48 PM MDT berni via Digitalmars-d-learn
wrote:
> On Saturday, 15 September 2018 at 03:25:38 UTC, Paul Backus wrote:
> > On Friday, 14 September 2018 at 20:43:45 UTC, SrMordred wrote:
> >> What you want is std.range.chunks
> >>
> >>
> >> auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
> >>
> >> a.map!(to!string)
> >>
> >> .join("")
> >> .chunks(4)
> >> .map!(to!string) //don´t know why the chunks are not
> >>
> >> already strings at this point ;/
> >>
> >> .writeln;
> >
> > It's easier if you chunk before joining:
> >
> > auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
> >
> > a.map!(to!string)
> >
> > .chunks(4)
> > .map!join
> > .writeln;
>
> Oh, thanks. What I didn't know about was join. Now I wonder how I
> could have found out about it, without asking here? Even yet I
> know it's name I cannot find it, nighter in the language
> documentation nor in the library documentation.
https://dlang.org/phobos/std_array.html#join
- Jonathan M Davis
Re: array to string functional?
On Saturday, 15 September 2018 at 03:25:38 UTC, Paul Backus wrote:
On Friday, 14 September 2018 at 20:43:45 UTC, SrMordred wrote:
What you want is std.range.chunks
auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
a.map!(to!string)
.join("")
.chunks(4)
.map!(to!string) //don´t know why the chunks are not
already strings at this point ;/
.writeln;
It's easier if you chunk before joining:
auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
a.map!(to!string)
.chunks(4)
.map!join
.writeln;
Oh, thanks. What I didn't know about was join. Now I wonder how I
could have found out about it, without asking here? Even yet I
know it's name I cannot find it, nighter in the language
documentation nor in the library documentation.
Re: array to string functional?
On Friday, 14 September 2018 at 20:43:45 UTC, SrMordred wrote:
What you want is std.range.chunks
auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
a.map!(to!string)
.join("")
.chunks(4)
.map!(to!string) //don´t know why the chunks are not
already strings at this point ;/
.writeln;
It's easier if you chunk before joining:
auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
a.map!(to!string)
.chunks(4)
.map!join
.writeln;
Re: array to string functional?
On Friday, 14 September 2018 at 19:44:37 UTC, berni wrote:
a) I've got an int[] which contains only 0 und 1. And I want to
end with a string, containing 0 and 1. So [1,1,0,1,0,1] should
become "110101". Of course I can do this with a loop and ~. But
I think it should be doable with functional style, which is
something I would like to understand better. Can anyone help me
here? (I think a.map!(a=>to!char(a+'0')) does the trick, but is
this good style or is there a better way?)
b) After having this I'd like to split this resulting string
into chunks of a fixed length, e.g. length 4, so "110101" from
above should become ["1101","01"]. Again, is it possible to do
that with functional style? Probably chunks from std.range
might help here, but I don't get it to work.
All in all, can you fill in the magic functional chain below?
auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
auto result = magic functional chain here :-)
assert(result==["1011","1010","","0"]);
What you want is std.range.chunks
auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0];
a.map!(to!string)
.join("")
.chunks(4)
.map!(to!string) //don´t know why the chunks are not already
strings at this point ;/
.writeln;
array to string functional?
a) I've got an int[] which contains only 0 und 1. And I want to end with a string, containing 0 and 1. So [1,1,0,1,0,1] should become "110101". Of course I can do this with a loop and ~. But I think it should be doable with functional style, which is something I would like to understand better. Can anyone help me here? (I think a.map!(a=>to!char(a+'0')) does the trick, but is this good style or is there a better way?) b) After having this I'd like to split this resulting string into chunks of a fixed length, e.g. length 4, so "110101" from above should become ["1101","01"]. Again, is it possible to do that with functional style? Probably chunks from std.range might help here, but I don't get it to work. All in all, can you fill in the magic functional chain below? auto a = [1,0,1,1,1,0,1,0,1,1,1,1,0]; auto result = magic functional chain here :-) assert(result==["1011","1010","","0"]);
