Re: Conditional sorting across two arrays
Rinku Mahesh wrote:
Hi,
I've two arrays of same depth (let it be 6)
1st Array:- @unique {11 , 23, 44, 66, 900, 1009} 2nd Array:- @occ_count {2,
77, 22, 2, 77,29}
Here I'm looking for a sorting mechanism with the following conditions:-
a. Sort 2nd Array in descending order such that it should reflect
{77,77,29,22,2,2}
b. The values of 1st array should also change in accordance with the
positions of elements of 2nd array such that sorting the 1st array should
reflect {23,900,1009,44,11,66}
23 and 900 or 11 and 66 can be interchanged but whatever value is lesser
should appear first in the list.
c. As there are repeatations in 2nd Array (77 and 2) there could be two
values associated with these elements in 1st array (23/900 or 11/66). Here 23
is lesser than 900 thus it should appear fist in the list.
If the above explaination is confusing I'm looking for a way where every
element of an array can be mapped to corresponding element of another array
and as a whole both the arrays require a sorting w.r.t. 2nd array.
Can anyone suggest an eficient way to implement same.
Hi Rinku
You need to sort a list of indices. Take a look at the code below which does
what you describe.
HTH,
Rob
use strict;
use warnings;
my @unique = (11, 23, 44, 66, 900, 1009);
my @occ_count = (2, 77, 22, 2, 77, 29);
my @idx = sort {
$occ_count[$b] = $occ_count[$a] or
$unique[$a] = $unique[$b]
} 0 .. $#unique;
@unique = @[EMAIL PROTECTED];
@occ_count = @[EMAIL PROTECTED];
foreach (0 .. $#unique) {
printf %4d - %2d\n, $unique[$_], $occ_count[$_];
}
**OUTPUT**
23 - 77
900 - 77
1009 - 29
44 - 22
11 - 2
66 - 2
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Re: Conditional sorting across two arrays
Hi Rinku,
Now I could try and explain this in my own words but I think this will help
you a lot more.
http://www.unix.org.ua/orelly/perl/advprog/ch02_02.htm
What you are looking for is a very common thing, your not the first to bump
into this problem :-)
Regards,
Rob
On 12/12/06, Rinku Mahesh [EMAIL PROTECTED] wrote:
Hi,
I've two arrays of same depth (let it be 6)
1st Array:- @unique {11 , 23, 44, 66, 900, 1009}
2nd Array:- @occ_count {2, 77, 22, 2, 77,29}
Here I'm looking for a sorting mechanism with the following conditions:-
a. Sort 2nd Array in descending order such that it should reflect
{77,77,29,22,2,2}
b. The values of 1st array should also change in accordance with the
positions of elements of 2nd array such that sorting the 1st array should
reflect {23,900,1009,44,11,66}
23 and 900 or 11 and 66 can be interchanged but whatever value is lesser
should appear first in the list.
c. As there are repeatations in 2nd Array (77 and 2) there could be two
values associated with these elements in 1st array (23/900 or 11/66). Here
23 is lesser than 900 thus it should appear fist in the list.
If the above explaination is confusing I'm looking for a way where every
element of an array can be mapped to corresponding element of another array
and as a whole both the arrays require a sorting w.r.t. 2nd array.
Can anyone suggest an eficient way to implement same.
TIA,
Rinku
-
Everyone is raving about the all-new Yahoo! Mail beta.
Re: Conditional sorting across two arrays
Rinku Mahesh schreef:
I've two arrays of same depth (let it be 6)
1st Array:- @unique {11 , 23, 44, 66, 900, 1009}
2nd Array:- @occ_count {2, 77, 22, 2, 77,29}
[...]
b. The values of 1st array should also change in accordance with
the positions of elements of 2nd array such that sorting the 1st
array should reflect {23,900,1009,44,11,66}
Why then are these values not stored in an AoA? (see perldsc)
my @x =
( [ 11, 2]
, [ 23, 77]
, [ 44, 22]
, [ 66, 2]
, [ 900, 77]
, [1009, 29]
) ;
--
Affijn, Ruud
Gewoon is een tijger.
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Re: Conditional sorting across two arrays
--- Rob Coops [EMAIL PROTECTED] wrote: Hi Rinku, Now I could try and explain this in my own words but I think this will help you a lot more. http://www.unix.org.ua/orelly/perl/advprog/ch02_02.htm What you are looking for is a very common thing, your not the first to bump into this problem :-) Please don't link to copyrighted work which has been posted to the Web in violation of said copyright. Writing a book is hard work and unless the author deliberately wants their book to be given away for free, we should respect the author's desire to earn a living. Cheers, Ovid -- Buy the book -- http://www.oreilly.com/catalog/perlhks/ Perl and CGI -- http://users.easystreet.com/ovid/cgi_course/ -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
RE: Conditional sorting across two arrays
Rinku Mahesh mailto:[EMAIL PROTECTED] wrote:
: If the above explaination is confusing I'm looking for a way
: where every element of an array can be mapped to corresponding
: element of another array and as a whole both the arrays require
: a sorting w.r.t. 2nd array.
M.J. Dominus wrote three slides about an Indirect Sort which
you may find helpful. He's using two arrays of names. One for
first names, one for last names. Basically, the idea is to sort
the array indexes and then apply the sorted indexes to each array
using an array slice. (I don't know if he's right about those APL
folks.)
http://perl.plover.com/yak/hw2/samples/slide003.html
In your case, you need a numerical comparison (=) on both
arrays as opposed to a string comparison (cmp). You also require
that ties be sorted on the other array. That can be performed
within the sort. One thing I like about sorting indexes is that
you can save the sorts.
use strict;
use warnings;
# Test data
my @unique= ( 66, 23, 44, 11, 900, 1009 );
my @occ_count = ( 2, 77, 22, 2, 77, 29 );
# Sort in ascending order, ascending order
# Use reverse for descending order, descending order
my @ascending_indexes =
sort {
$occ_count[$a] = $occ_count[$b]
||
$unique[$a] = $unique[$b]
} 0 .. $#occ_count;
# Sort in descending order, ascending order
# Use reverse for ascending order, descending order
my @descending_indexes =
sort {
$occ_count[$b] = $occ_count[$a]
||
$unique[$a] = $unique[$b]
} 0 .. $#occ_count;
# Reports
print Ascending sort then ascending sort:\n\t;
printf '%5d', $_ foreach @occ_count[ @ascending_indexes ];
print \n\t;
printf '%5d', $_ foreach @unique[ @ascending_indexes ];
print \n\n;
print Ascending sort then descending sort\n\t;
printf '%5d', $_ foreach @occ_count[ reverse @descending_indexes ];
print \n\t;
printf '%5d', $_ foreach @unique[ reverse @descending_indexes ];
print \n;
print Descending sort then descending sort:\n\t;
printf '%5d', $_ foreach @occ_count[ reverse @ascending_indexes ];
print \n\t;
printf '%5d', $_ foreach @unique[ reverse @ascending_indexes ];
print \n\n;
print Descending sort then ascending sort\n\t;
printf '%5d', $_ foreach @occ_count[ @descending_indexes ];
print \n\t;
printf '%5d', $_ foreach @unique[ @descending_indexes ];
print \n;
__END__
For larger arrays, you might want to transform one array
first.
HTH,
Charles K. Clarkson
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Re: Conditional sorting across two arrays
On Tue, December 12, 2006 6:25 am, Ovid wrote: --- Rob Coops [EMAIL PROTECTED] wrote: Hi Rinku, Now I could try and explain this in my own words but I think this will help you a lot more. What you are looking for is a very common thing, your not the first to bump into this problem :-) Please don't link to copyrighted work which has been posted to the Web in violation of said copyright. Writing a book is hard work and unless the author deliberately wants their book to be given away for free, we should respect the author's desire to earn a living. It was also linked it in your reply, which was a violation of your violation. -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
Re: Conditional sorting across two arrays
On 12/12/2006 04:00 AM, Rinku Mahesh wrote:
Hi,
I've two arrays of same depth (let it be 6)
1st Array:- @unique {11 , 23, 44, 66, 900, 1009}
2nd Array:- @occ_count {2, 77, 22, 2, 77,29}
Here I'm looking for a sorting mechanism with the following conditions:-
a. Sort 2nd Array in descending order such that it should reflect {77,77,29,22,2,2}
b. The values of 1st array should also change in accordance with the positions of elements of 2nd array such that sorting the 1st array should reflect {23,900,1009,44,11,66}
23 and 900 or 11 and 66 can be interchanged but whatever value is lesser should appear first in the list.
c. As there are repeatations in 2nd Array (77 and 2) there could be two values associated with these elements in 1st array (23/900 or 11/66). Here 23 is lesser than 900 thus it should appear fist in the list.
If the above explaination is confusing I'm looking for a way where every element of an array can be mapped to corresponding element of another array and as a whole both the arrays require a sorting w.r.t. 2nd array.
Can anyone suggest an eficient way to implement same.
TIA,
Rinku
I hope this is both easy and efficient enough for you:
use strict;
use warnings;
use Sort::Key qw(nkeysort);
my (@unique, @occ_count);
@unique = (66 , 23, 44, 11, 900, 1009);
@occ_count = (2, 77, 22, 2, 77,29);
my @indexes = nkeysort { $occ_count[$_] * 1 + $unique[$_] }
(0..$#occ_count);
@unique = map $unique[$_], @indexes;
@occ_count = map $occ_count[$_], @indexes;
print @unique\n;
print @occ_count\n;
The line where @indexes is assigned is probably the most confusing, so
I'll only explain that one. Sort::Key allows you to sort while
specifying your key field in an easy and natural manner. Because I want
to sort two arrays, I have to sort array indexes--not the arrays
themselves; that's what (0..$#occ_count) does; it creates a list of
array indexes.
Inside of the { ... }, I specify the key field on which to sort. The
easy way to do this would be to use { $occ_count[$_] }, but that would
only sort the array indexes based on what's in @occ_count, and I have to
take @unique into consideration also, so I make the occ_count part of
the forumula much more important than the unique part of the forumla
by multiplying $occ_count[$_] by 1; this should put it well above
the range of numbers in @unique.
Then nkeysort tells Sort::Key to do a numeric sort.
HTH
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