Dear newbio,

While many answers have been given above, every one of them is a quadratic-time solution (Update: Oops! didn't see throop's solution, which is also linear time as pointed out by ikegami. I guess I was writing while throop was posting.). The first removal shifts the top elements of the array down by 1. The next shifts more (including shifting the same previous elements once again), ...). On the other hand these operations are fast enough, that clarity and elegance of code may be reasons enough to not worry about efficiency.

While not as elegant as the previous entries, here is a linear time solution (I am assuming that @arrayindex is a reverse sorted & unique'd list. If not, use Grandfather's technique in Re^4: Remove array elements dynamically! (reverse)). At the end of the loop, the answer is stored in @newarray and @array is empty. 

my @newarray = ();
foreach my $i (@arrayindex)
{ unshift @newarray, (splice @array, $i);
  pop @array;
}

[download]
Note that while we are not doing this inplace, there is no memory hit, because the @newarray grows, just as @array shrinks.

In reply to Re: Remove array elements dynamically! by b4swine
in thread Remove array elements dynamically! by newbio

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


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.