RE: Obtaining a slice of unique values from an array
Thanks Sudarshan, Felix!! This is one of the area that I never had to look. But as
the saying goes...curiosity kills the crow...I am now all into it!!
Thanks again!!
-Original Message-
From: Felix Geerinckx [mailto:[EMAIL PROTECTED]]
Sent: Monday, July 01, 2002 10:02 AM
To: [EMAIL PROTECTED]
Subject: RE: Obtaining a slice of unique values from an array
on Mon, 01 Jul 2002 13:45:30 GMT, [EMAIL PROTECTED] (Shishir
K. Singh) wrote:
> This is the example "d" cited in perldoc -q duplicate
> d) A way to do (b) without any loops or greps:
[line numbers added for reference]
> 01undef %saw;
> 02@saw{@in} = ();
> 03@out = sort keys %saw; # remove sort if undesired
>
> I am a bit confused about this example ??
You need to learn about hash-slices, e.g. from Uri Guttman's article
at
<http://tlc.perlarchive.com/articles/perl/ug0001.shtml>
What's happening?
line 01 makes sure you start with an empty hash
line 02 creates a key-value pair in %saw foreach element of @in. The
value is undef (because of the '()' on the rhs, but who
cares ;-). The essential part here is that a hash cannot
have duplicate keys.
line 03 puts the keys (which are unique by definition) in @out
--
felix
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RE: Obtaining a slice of unique values from an array
on Mon, 01 Jul 2002 13:45:30 GMT, [EMAIL PROTECTED] (Shishir
K. Singh) wrote:
> This is the example "d" cited in perldoc -q duplicate
> d) A way to do (b) without any loops or greps:
[line numbers added for reference]
> 01undef %saw;
> 02@saw{@in} = ();
> 03@out = sort keys %saw; # remove sort if undesired
>
> I am a bit confused about this example ??
You need to learn about hash-slices, e.g. from Uri Guttman's article
at
What's happening?
line 01 makes sure you start with an empty hash
line 02 creates a key-value pair in %saw foreach element of @in. The
value is undef (because of the '()' on the rhs, but who
cares ;-). The essential part here is that a hash cannot
have duplicate keys.
line 03 puts the keys (which are unique by definition) in @out
--
felix
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
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Re: Obtaining a slice of unique values from an array
"Shishir K. Singh" wrote:
> >on Sun, 30 Jun 2002 12:08:23 GMT, Dan Fish wrote:
>
> > What is the most efficient (or at least AN efficient :-) way of
> > obtaining a slice from an array wherein the slice contains only
> > unique values found in the array?
>
> >See
> > perldoc -q duplicate
>
> --
> >felix
> This is the example "d" cited in perldoc -q duplicate
> d) A way to do (b) without any loops or greps:
>
> undef %saw;
> @saw{@in} = ();
This is called a hash slice, this is same as writing
foreach (@in) { $saw{$_} = undef }
>
> @out = sort keys %saw; # remove sort if undesired
>
> I am a bit confused about this example ??
>
> --
> To unsubscribe, e-mail: [EMAIL PROTECTED]
> For additional commands, e-mail: [EMAIL PROTECTED]
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RE: Obtaining a slice of unique values from an array
>on Sun, 30 Jun 2002 12:08:23 GMT, Dan Fish wrote:
> What is the most efficient (or at least AN efficient :-) way of
> obtaining a slice from an array wherein the slice contains only
> unique values found in the array?
>See
> perldoc -q duplicate
--
>felix
This is the example "d" cited in perldoc -q duplicate
d) A way to do (b) without any loops or greps:
undef %saw;
@saw{@in} = ();
@out = sort keys %saw; # remove sort if undesired
I am a bit confused about this example ??
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Re: Obtaining a slice of unique values from an array
On Jun 30, Dan Fish said: >What is the most efficient (or at least AN efficient :-) way of obtaining a >slice from an array wherein the slice contains only unique values found in >the array? >if @array = (1,3,5,5,3,5,2,1) then @slice = (1,3,5,2) This is FAQ. perldoc -q unique Found in /usr/local/lib/perl5/5.00502/pod/perlfaq4.pod How can I extract just the unique elements of an array? -- Jeff "japhy" Pinyan [EMAIL PROTECTED] http://www.pobox.com/~japhy/ RPI Acacia brother #734 http://www.perlmonks.org/ http://www.cpan.org/ ** Look for "Regular Expressions in Perl" published by Manning, in 2002 ** what does y/// stand for? why, yansliterate of course. [ I'm looking for programming work. If you like my work, let me know. ] -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Obtaining a slice of unique values from an array
on Sun, 30 Jun 2002 12:08:23 GMT, Dan Fish wrote: > What is the most efficient (or at least AN efficient :-) way of > obtaining a slice from an array wherein the slice contains only > unique values found in the array? See perldoc -q duplicate -- felix -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
