I am interested to learn the fastest and shortest way to convert a
textfile-like string to an array and back again (chopping newlines).
Test program follows. Improvements (golf or speed) welcome.
/-\
use strict;
my $x = <<'FLAMING_OSTRICHES';
This is first test line
This is 2nd
And 3rd
FLAMING
* Andrew Savige <[EMAIL PROTECTED]> [2003-02-07 13:47]:
> my @lines = split(/^/, $x, -1); chomp(@lines); # fastest?
my @lines = split m[\Q$/], $x, -1;
--
Regards,
Aristotle
On Fri, Feb 07, 2003 at 06:26:22PM +1100, Andrew Savige wrote:
> my @lines = split(/^/, $x, -1); chomp(@lines); # fastest?
I'll prolly say something stupid here, but:
my @lines = split "\n", $x;
Joy,
`/.
--
"There are people in the world so hungry, that God cannot appear
Andrew Savige <[EMAIL PROTECTED]> wrote:
> I am interested to learn the fastest and shortest way to convert a
> textfile-like string to an array and back again (chopping newlines).
Not tested, but I would guess that the obvious
@lines = split /\n/, $x, -1; pop @lines;
might be both fastest a
> -Original Message-
> From: Andrew Savige [mailto:[EMAIL PROTECTED]]
>
> I am interested to learn the fastest and shortest way to convert a
> textfile-like string to an array and back again (chopping newlines).
> Test program follows. Improvements (golf or speed) welcome.
# String to arr
* John Douglas Porter <[EMAIL PROTECTED]> [2003-02-07 14:15]:
> @lines = split /\n/, $x, -1; pop @lines;
$/ can be different from \n though.
And popping the last field is dangerous - you don't know if
the file ends with a newline. Also, you now have no chance
to reconstruct the exact equivalent
"A. Pagaltzis" <[EMAIL PROTECTED]> wrote:
> * John Douglas Porter <[EMAIL PROTECTED]> [2003-02-07 14:15]:
> > @lines = split /\n/, $x, -1; pop @lines;
>
> $/ can be different from \n though.
Yes, but his example data was text in a here document.
But you can always do
split m,$/, $x, -1;
* John Douglas Porter <[EMAIL PROTECTED]> [2003-02-07 14:50]:
> Yes, but his example data was text in a here document.
Then add a note about the caveat.
> split m,$/, $x, -1;
In bizarre cases, $/ might contain regex metacharacters.
Don't forget the \Q.
> > And popping the last field is danger
"A. Pagaltzis" <[EMAIL PROTECTED]> wrote:
> John Douglas Porter <[EMAIL PROTECTED]>:
> > Yes, but his example data was text in a here document.
> Then add a note about the caveat.
Sorry, I thought (and still do) that the OP's caveat was
understood to still be in effect.
> > join "\n", @lines
On Fri, 7 Feb 2003 15:05:47 +0100, [EMAIL PROTECTED] wrote:
>Not if the last line did not end with a record separator.
>His example data did, but other data might not.
In general, I'm all in favor of coding charitably toward files w/o a
trailing newline. Here, however, the OP wants to convert dat
Yitzchak Scott-Thoennes <[EMAIL PROTECTED]> wrote:
> chomp( my $tmp = $x );
> my @lines = split /\n/, $tmp, -1;
Ah, yes, of course! Yitzchak++
--
John Douglas Porter
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* Yitzchak Scott-Thoennes <[EMAIL PROTECTED]> [2003-02-07 20:51]:
> chomp(my $tmp=$x); my @lines=split /\n/,$tmp,-1
Very nice.
--
Regards,
Aristotle
On Fri, 7 Feb 2003, A. Pagaltzis wrote:
> * John Douglas Porter <[EMAIL PROTECTED]> [2003-02-07 14:50]:
>
> > join "\n", @lines, $tail;
>
> Unfortunately, that won't work either - regardless of the
> value of $tail - even undef -, you are joining an extra
> element onto the string.
Yes it doe
Aristotle wrote:
> my @lines = split m[\Q$/], $x, -1;
This one produces one too many elements in the array.
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`/anick wrote:
> I'll prolly say something stupid here, but:
>
> my @lines = split "\n", $x;
This one prolly erroneously removes empty trailing lines.
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- Send some online love this Valentine's Day.
Winter Christian wrote:
> # String to array:
> @lines=$x=~/[^\n]/g;
This one splits into array of chars not array of lines.
/-\
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Yitzchak Scott-Thoennes wrote:
> chomp(my $tmp=$x); my @lines=split /\n/,$tmp,-1
This one fails for the case $x = "\n"; @lines should contain one
empty element, but the code above contains none.
/-\
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- Send some online love this Valentine's D
To clarify, you may assume that lines in string are separated by
"\n" but any solution must pass the following edge cases:
1) empty string: @lines should contain zero elements
2) string of "\n" : @lines should contain one empty element
3) trailing empty lines should be retained
4) you may not a
To convert the other way is simpler and I'm struggling to find
alternatives to my original join solution. The only edge case I
can think of is empty array @lines. You may assume that no item
of @lines contains "\n". Benchmark program follows.
use strict;
use Benchmark;
my @lines = (
"",
"This
On Sun, 9 Feb 2003 12:34:38 +1100 (EST), [EMAIL PROTECTED] wrote:
>Yitzchak Scott-Thoennes wrote:
>> chomp(my $tmp=$x); my @lines=split /\n/,$tmp,-1
>
>This one fails for the case $x = "\n"; @lines should contain one
>empty element, but the code above contains none.
Sigh. I'd call that a bug
On Sun, 9 Feb 2003 14:34:07 +1100 (EST), [EMAIL PROTECTED] wrote:
>sub a2 { my $y = ""; $y .= $_ . "\n" for @lines }
The ="" is optional. my $x; $x.="foo" intentionally doesn't warn.
Andrew savige wrote:
>
> sub a1 { my @lines = split(/^/, $x, -1); chomp(@lines) }
> sub a2 { my @lines = $x eq "" ? () : $x =~ /^.*/mg }
> sub j1 { my @lines = map { chomp; $_ } split /^/, $x, -1 }
> # w1 is Perl 5.8.0 only
> sub w1 { open(my $fh, "<", \$x); my @lines = <$fh>; chomp(@lines) }
> ti
* John W. Krahn <[EMAIL PROTECTED]> [2003-02-09 12:27]:
> You can also speed up j1 by using map without the braces.
>
> sub j1 { my @lines = map chomp && $_, split /^/, $x, -1 }
Which will promptly fail on a last line without a trailing
record separator because chomp would return 0 and cause the
Yitzchak Scott-Thoennes wrote:
> Sigh. I'd call that a bug if someone hadn't gone to the trouble to
> test for it and document it. (Indeed, I see a bug report out there:
> #6653, was 20010327.008.) So do something like:
>
> my @lines;
> chomp(my $tmp=$x);
> @lines = split /\n/,$tmp,-1 or @lines=
@lines = length($x) ? $x=~/^(.*)$/mg : ();
--
John Douglas Porter
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John Douglas Porter wrote:
> @lines = length($x) ? $x=~/^(.*)$/mg : ();
^ ^^
unnecessary
This is a little faster:
@lines = length($x) ? $x=~/^.*/mg : ();
/-\
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John Douglas Porter:
> @lines = length($x) ? $x=~/^(.*)$/mg : ();
@lines = ($x=~/^.*/mg) x !!length($x);
@lines = ($x=~/^.*/mg) x ($x ne "");
This line of play looks promising for golf.
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* Andrew Savige <[EMAIL PROTECTED]> [2003-02-10 07:28]:
> @lines = ($x=~/^.*/mg) x !!length($x);
$_=$x;@lines=(/^.*/mg)x+length;
--
Regards,
Aristotle
Aristotle:
> > @lines = ($x=~/^.*/mg) x !!length($x);
>
> $_=$x;@lines=(/^.*/mg)x+length;
*whistle* *whistle* *red card* *disqualified*
multiplying by length (x+length) will not give the desired result here;
it must be boolean (0 or 1 only).
/-\
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Aristotle golfed:
> $_=$x;@lines=(/^.*/mg)x+length;
Against my better judgment, I will have a go at golfing this:
$_=$x;@l=(/^.*/mg)x/./s
/-\
http://greetings.yahoo.com.au - Yahoo! Greetings
- Send some online love this Valentine's Day.
* Andrew Savige <[EMAIL PROTECTED]> [2003-02-10 17:54]:
> *whistle* *whistle* *red card* *disqualified*
> multiplying by length (x+length) will not give the desired
> result here; it must be boolean (0 or 1 only).
Doh! Of course. I'm an idiot. *grmbl*
--
Regards,
Aristotle
Andrew Savige schreef:
> Aristotle golfed:
> > $_=$x;@lines=(/^.*/mg)x+length;
>
> Against my better judgment, I will have a go at golfing this:
>
> $_=$x;@l=(/^.*/mg)x/./s
This clobbers $_. Not nice for the rest of the program. Correct is:
{local$_=$x;@l=(/^.*/mg)x/./s}
or
@l=(/^.*/
* Eugene van der Pijll <[EMAIL PROTECTED]> [2003-02-10 18:35]:
> Unfortunately, you had "use strict" in your first post,
> and neither of these are use-strict safe.
Oh? What makes you say so?
--
Regards,
Aristotle
(-ugene sprak:
> Andrew Savige schreef:
> > Aristotle golfed:
> > > $_=$x;@lines=(/^.*/mg)x+length;
> >
> > Against my better judgment, I will have a go at golfing this:
> >
> > $_=$x;@l=(/^.*/mg)x/./s
>
> This clobbers $_. Not nice for the rest of the program. Correct is:
>
> {local$_=$
On Mon, 10 Feb 2003 11:09:25 +1100 (EST), [EMAIL PROTECTED] wrote:
>Yitzchak Scott-Thoennes wrote:
>> Sigh. I'd call that a bug if someone hadn't gone to the trouble to
>> test for it and document it. (Indeed, I see a bug report out there:
>> #6653, was 20010327.008.) So do something like:
>>
>>
Yitzchak Scott-Thoennes <[EMAIL PROTECTED]> wrote:
> Only if you say $x eq "" means no lines instead of one empty
> line missing its "\n" :)
Well, the subject line does say "textfile-like", and a 0-byte
text file has no lines, not one empty line.
--
Keith C. Ivey <[EMAIL PROTECTED]>
Washington
On Mon, 10 Feb 2003 23:44:14 -0500, [EMAIL PROTECTED] wrote:
>Yitzchak Scott-Thoennes <[EMAIL PROTECTED]> wrote:
>
>> Only if you say $x eq "" means no lines instead of one empty
>> line missing its "\n" :)
>
>Well, the subject line does say "textfile-like", and a 0-byte
>text file has no lines, n
On Tue, 11 Feb 2003 at 10:39:53 +1100, Andrew Savige wrote:
> In case anyone is unaware of (-ugene's status in world golf, you can
> find out by typing in Eugene van der Pijll at www.googlism.com.
I just typed in 'Eugene' to check.
eugene is the fastest and most pleasant
eugene is about the size
Ian Phillipps sprak:
> I just typed in 'Eugene' to check.
>
> eugene is the fastest and most pleasant
> eugene is about the size of a dog
> eugene is devastated
>
> But, most relevantly,
>
> eugene is right
In my experience, Eugene (and Ton) are always right.
I just noticed that Yitzchak's emai
Andrew Savige [mailto:[EMAIL PROTECTED]] wrote:
> Winter Christian wrote:
> > # String to array:
> > @lines=$x=~/[^\n]/g;
>
> This one splits into array of chars not array of lines.
Shame on me, seems like I was unable to
read what the question was.
-Christian
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