Nah makes perfect sense !! ;) Grep Power(tm)
-----Original Message----- From: Ankur Gupta [mailto:[EMAIL PROTECTED] Sent: 27 January 2005 13:15 To: Manav Mathur Cc: Rob Napier (rnapier); Richard Chycoski (rac); Mallikarjun Kodicherla (mkodiche); perl-trolls (mailer list); beginners@perl.org Subject: Re: How to find the Index of an element in array? I have another solution using grep but its kinda weird.... @array = (..................); #your array here $i=1; eval{ grep { (/$element/o && die ) or ++$i } @array; }; print "index of $element = $i\n"; #prints the index of $element.. If $i > scalar(@array), element not found. -- Ankur Manav Mathur wrote: >Rob, In your solution >$hash{'pqr'} will return 3. >- iniitalize $i with 1 >or >- >%hash=map{$_=>[EMAIL PROTECTED]; > >Manav > >|-----Original Message----- >|From: Rob Napier [mailto:[EMAIL PROTECTED] >|Sent: Thursday, January 27, 2005 2:06 PM >|To: Richard Chycoski >|Cc: Mallik; Perl-Trolls; beginners@perl.org >|Subject: Re: How to find the Index of an element in array? >| >| >|In terms of time efficiency, if you only need one lookup, the linear >|walk is almost certainly faster, since you don't have to hash the >|entire list. You can stop as soon as you find the answer (which you >|expect to be half-way down the list). But the speed difference is >|almost certainly negligable. In terms of space efficiency the array is >|much smaller too which matters if the hash gets particularly large >|(large enough that the speed difference isn't negligable). >| >|I agree with "depending on what else you need to do with your data." >|If a list is more natural for the data, definitely leave it in a list >|and just walk it. If you need to do a lot of lookups (or other >|hash-like things), you can hash the list as Richard suggests pretty easily: >| >|my $i = 0; >|my %hash = map { $_ => $i++ } @list; >|print $hash{$search}; >| >|And of course the above is short and simple, so maybe that's nice even >|if you're only doing it once and don't mind being slower and bigger >|(memorywise). >| >|If you want to stay with a fast linear search, there have been a >|couple of good suggestions. Tapasranjan's version is close, but does >|too much searching. You should do a 'last' after you've found the >|data. Arjun's solution is good, or you can do this kind of shortened form: >| >|my $search = 'pqr'; >|for(my $i = 0; $i < @arr; $i++) >|{ >| ($arr[$i] eq $search) && do { print "index is == $i\n"; last } } >| >|Note that in this form, $i is not valid outside the loop. You'll need >|to move the "my $i" outside the for() loop if you need it later in the code. >| >|-RobN >| >|Richard Chycoski wrote: >|> You would have to 'walk' the whole array, which is rather inefficient. >|> However, depending on what else you need to do with your data, a >|> hash could do better than an array: >|> >|> %myhash = ('abc'=>1, 'xyz'=>2, 'mno'=>3, 'pqr'=>4, 'stu'=>5, >|> 'sdfd'=>6); >|> >|> and then >|> $myhash{ 'pqr') wiil return 4. >|> >|> - Richard >|> >|> >|> Mallik wrote: >|> >|>> I need to find the index of a particular element in array. >|>> For eg., >|>> @arr = ('abc', 'xyz', 'mno','pqr','stu','sdfd'); >|>> >|>> I want to find the index of the element 'pqr' which is 4. >|>> >|>> Any function/code to achieve this. >|>> >|>> Thanks in advance, >|>> Mallik. >|>> >|>> >|> >| >|-- >|To unsubscribe, e-mail: [EMAIL PROTECTED] For additional >|commands, e-mail: [EMAIL PROTECTED] <http://learn.perl.org/> >|<http://learn.perl.org/first-response> >| >| > >********************************************************* >Disclaimer: > >This message (including any attachments) contains confidential >information intended for a specific individual and purpose, and is >protected by law. >If you are not the intended recipient, you should delete this message >and are hereby notified that any disclosure, copying, or distribution >of this message, or the taking of any action based on it, is strictly >prohibited. > >********************************************************* >Visit us at http://www.mahindrabt.com > > > > -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] <http://learn.perl.org/> <http://learn.perl.org/first-response>
