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# Sychronized sorting?

Posted on 2002-05-07
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Hello, I have a list of users and their "points", however i have tried to come up with a sorting script (using bubble sort, eww...) a few times and have failed, can someone please show me an example script that would sort data that looks like this?

BTAnamedERIK:107
RonJonSSE:57
Oz7656:1
tkdman401:25
Sou1Tear:5
EZMONEY80:20
AngelStr641:2
IronmanGus:1
cEDGabriel:3
PaPaloche:4
Infested2010:2
Danamajr:2
JeeStringDiva:1
MRitchie02:1
LilCGShuo2J:2
CGorg:1
Canivour:2
WutUpKneegroe:2
PoEbAbY3424:2
MusaUGA32:4
GreatGodlyOne:2

thank you very much.
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Question by:PitViper
• 4
• 2

LVL 8

Expert Comment

open IN, "datat.txt";  #this would be file containing data
@i=<IN>;

print "sorted alpha, case insensitive\n\n";
@o=sort {uc(\$a) cmp uc(\$b)} @i;
print @o;
print "\n\nthis is sorted by the number at the end";
@o=sort {substr(\$a,index(\$a,':')+1) <=> substr(\$b,index(\$b,':')+1)} @i;
print @o;
0

LVL 84

Expert Comment

In what order do you want them sorted?
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Author Comment

bebonham - the points are your if you can explain your answer a little, it works but thats some advanced code and i'm having a hard time dissecting it. Thanks :)
0

LVL 8

Accepted Solution

bebonham earned 200 total points
sorting is easy once you get the hang of it.

first:

sort works like this

@sorted_list=sort {comparison} @list_to_sort;

the default sort is alpha, and case sensitive.

perl uses \$a and \$b as references to each of the sets of two items that get compared.

so, @output= sort {\$a <=> \$b} @input;

would numerically sort @input into @output.

this line here,
@o=sort {substr(\$a,index(\$a,':')+1) <=> substr(\$b,index(\$b,':')+1)} @i;

takes whatever is after the ':' (substr(\$a,index(\$a,':')+1))

and compares it against the same from item two - substr(\$b,index(\$b,':')+1)

the part about {uc(\$a) cmp uc(\$b)} just converts the data to upper case, so the comparison is case sensitive.
keep in mind, anything you do to the list in the sort subroutine doesn't modify the actual data, it only tells sort what order to put it in.

if you have other questions, please look here
http://www.perldoc.com/perl5.6.1/pod/func/sort.html

thanks,

Bob
0

LVL 8

Expert Comment

correction....this
"the part about {uc(\$a) cmp uc(\$b)} just converts the data to upper case, so the comparison is case sensitive.
keep in mind, anything you do to the list in the sort subroutine doesn't modify "

should say the it makes the comparision NOT case sensitive
0

Author Comment

thanks, is it possible to get it into a hash with eaze? i.e. \$mypoints{\$name}, would make life a lot easier :) thanks again.
0

LVL 8

Expert Comment

heck yeah!!

, but keep in mind then it isn't sorted anymore...

open IN, "datat.txt";
@i=<IN>;

foreach(@i)
{
chomp(\$myPoints{substr(\$_,0,index(\$_,':'))}=substr(\$_,index(\$_,':')+1));
}
@k=keys %myPoints;
foreach(@k)
{
print "this dude " . \$_ . " he has " . \$myPoints{\$_} . " points.\n";
}

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