Beefy Boxes and Bandwidth Generously Provided by pair Networks
Your skill will accomplish
what the force of many cannot

comment on

( [id://3333] : superdoc . print w/replies, xml ) Need Help??
This is the solution I put together. I'm not sure how speedy it is in relation to the other suggestions in this thread, but as long as no album has more than a few thousand images, I suspect this method should be the fastest solution.

If anyone has further ideas to tighten this up or yet other alternative approaches, I'm eager for you to share them with me.
# Elsewhere in the code, we get an img_id, do a SELECT to find what # album_id it belongs to, then use the SELECT below to get all of # the img_id's that belong to that album. We use flattenArray() to # turn the arrayref from DBI into a plain old array. my @image_idx = flattenArray( @{$dbh->selectall_arrayref("SELECT img_i +d FROM images WHERE album_id = $image_id")}); # Find what place our target img_id is in the array. my $idx_loc = indexArray($img_id, @image_idx); # Get img_id's from array that come before and after the target. my $prev_img = $image_idx[$idx_loc - 1]; my $next_img = $image_idx[$idx_loc + 1]; # Thanks to merlyn, tilly and particle # sub flattenArray { my @flattened; # Will be in reverse order while (@_) { my $last = pop; if (UNIVERSAL::isa($last, "ARRAY")) { push @_, @$last; } else { push @flattened, $last; } } return reverse @flattened; } # My apologies, but I took this from a golf thread on PM. I've lost # the node number and apologize to the author. Please let me know # so I can credit you for this. sub indexArray(@) { my $s=shift; $_ eq $s && return @_ while $_=pop; -1; }

In reply to Solution - Re: Building an index for next/last in a photo album. by Seumas
in thread Building an index for next/last in a photo album. by Seumas

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.