July 24, 2008 03:57am pdt

1. Adam314 470,034
2. ozo 332,538
3. FishMonger 102,215
4. Tintin 77,315
5. hielo 57,450
6. mjcoyne 52,693
7. nedfine 27,740
8. ravenpl 24,680
9. clockwat... 22,660
10. teraplane 22,380
11. ahoffmann 18,924
12. oleber 18,450
13. kawas 18,300
14. suhasbha... 15,250
15. marchent 12,540

1. ozo 3,604,303
2. Adam314 1,392,453
3. Tintin 725,609
4. kandura 579,965
5. jmcg 517,810
6. mjcoyne 504,831
7. FishMonger 454,849
8. maneshr 385,976
9. teraplane 366,588
10. manav_ma... 338,348
11. clockwat... 238,948
12. rj2 211,481
13. ahoffmann 204,487
14. davorg 153,165
15. Tim_Utschig 113,107

04.01.2008 at 11:10AM PDT, ID: 23286704

	[x] Attachment Details

Sorting a file using Perl

Asked by rdashokraj in Perl Programming Language, Unix Operating Systems

Hello,

I have a file like given in the snippet, please let me know how can I do numeric sort w.r.t value in the second column (in descending order)?

Thanks,
AshokStart Free Trial

         
           
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             usr/local/NETAPP/740/611R2_sysfiles_a.tar          33710.00 KB
/usr/local/NETAPP/740/fw.rom                       245.67 KB
/usr/local/NETAPP/740/filer-mrtg.tar               2007.50 KB
/usr/local/RSA/upgrade                              3.96 KB
/usr/local//RSA/ACE_SERVER/aceserver_3.3_p09_hp.tar.gz     19024.70 KB
 
/usr/local/RSA/ACE_SERVER/aceserver_3.3_p09_ra.exe         2293.89 KB
/usr/local/RSA/ACE_SERVER/aceserver_4.1_sol5.8.tar         171.00 KB
 
/usr/local/RSA/README/readme.p09.ra.txt                    2.12 KB
/usr/local/archives/README/readme.p09.txt                  4.51 KB
 
/usr/local/RSA/ACE_CLIENT/ACE_Client-3.3.hp.tar.gz         5495.71 KB
/usr/local/RSA/ACE_CLIENT/ACE_Client-4.1.hpux.tar.gz       4127.99 KB
 
/usr/local/RSA/ACE_CLIENT/ACE_Client_4.1.aix.tar.gz         1970.00 KB
 
/usr/local/RSA/ACE_CLIENT/ACE_Client-4.1.sol.tar            2020.00 KB

           
         

Keywords: Sorting a file using Perl

	Title
1	Numeric Sorting in a ListView
2	Sort by ascending/descending not av…
3	Sort Datagridview column programmati…
4	Table Sort Order Ascending - Descen…
5	Sort Column Values by Number, Then…
6	Sort datatable

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Input
EE Bugs

04.01.2008 at 11:24AM PDT, ID: 21256662

ozo:

perl -e 'print sort{(split" ",$b)[1] <=> (split" ",$a)[1]}<>'

Assisted Solution

04.02.2008 at 12:23AM PDT, ID: 21260742

nedfine:

another way :

open IN, "sort.txt" or die "cannot open input file";
while(<IN>){
@a = split/\s+/;
$hash{$a[0]} = $a[1];}
foreach (sort { $b <=> $a } values %hash) {
$temp = $_;
foreach (keys %hash) {
print "$_ $temp\n" if($hash{$_} == $temp);}}
close IN;

Thanks
Ned

Accepted Solution

04.02.2008 at 01:40AM PDT, ID: 21261070

ozo:

That's an O(n²) algorithm
Better might be

open IN, "sort.txt" or die "cannot open sort.txt $!";
while(<IN>){
push @{$hash{(split)[1]}},$_;
}
close IN;
print @{$hash{$_}} foreach sort { $b <=> $a } keys %hash;

or
perl -le 'print /\s(.*)/ for reverse sort map{/(\S*\s+((\d*)\.?\d*).*)/&&chr(33+length $3)."$2 $1"}<>'

Assisted Solution

04.02.2008 at 06:20AM PDT, ID: 21262696

rdashokraj:

All your scripts are working perfectly fine. But it seems like a magic for me. Could you please explain atleast the first syntax: perl -e 'print sort{(split" ",$b)[1] <=> (split" ",$a)[1]}<>'

Then I observed the variables $b and $a used in all the scripts. What does it do?
And what does the [1] denotes? Please explain.
I can understand the symbol <=> used for sorting.

ozo

04.02.2008 at 11:45AM PDT, ID: 21266116

perldoc -f sort
...
If the subroutine's prototype is "($$)", the elements to be
compared are passed by reference in @_, as for a normal
subroutine. This is slower than unprototyped subroutines,
where the elements to be compared are passed into the
subroutine as the package global variables $a and $b (see
example below). Note that in the latter case, it is usually
counter-productive to declare $a and $b as lexicals.

perldoc perlop
...
Equality Operators
...
Binary "<=>" returns -1, 0, or 1 depending on whether the left argument
is numerically less than, equal to, or greater than the right argument.
If your platform supports NaNs (not-a-numbers) as numeric values, using
them with "<=>" returns undef. NaN is not "<", "==", ">", "<=" or ">="
anything (even NaN), so those 5 return false. NaN != NaN returns true,
as does NaN != anything else. If your platform doesn't support NaNs
then NaN is just a string with numeric value 0.

perldoc perldata
...
$days[28] # the 29th element of array @days
...
List value constructors
...
A list value may also be subscripted like a normal array. You must put
the list in parentheses to avoid ambiguity. For example:

20080716-EE-VQP-32 / EE_QW_2_20070628

Sorting a file using Perl

Asked by rdashokraj in Perl Programming Language, Unix Operating Systems

About this solution