If original order doesn't matter try this approach. Broadly, it indexes the array items by using as key the first word. If an key becomes duplicated the item is removed. In detail it uses a hash where keys are the first word of every line in the array. If it tries to add a hash item that does exist (ie, a duplicated key) it sets the hash value to empty string. Finally it filters the hash values discarding those being an empty string.

my @array = (
"hello 1234 5698 7458",
"hi 1457 7459 6214",
"good_day 1458",
"hi 1258 3658",
"good_morning 4758",
"hi 1453",
);

my %indexedArray;
my $key;

foreach (@array) {
    $key = (split())[0];
    if ( defined $indexedArray{$key} ) {
        $indexedArray{$key} = '';
    }
    else {
        $indexedArray{$key} =  $_;
    }
}

@array = grep(/.+/,values(%indexedArray));

[download]

In reply to Re: Removing certain lines from array by VGavara
in thread Removing certain lines from array by Dr Manhattan

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.