You got the levels wrong. Change $s->{BLOCKS} to $p->{BLOCKS} and $b->{PDB_ID} to $p->{PDB_ID} and $blocks[$p][$b]{PSTART} to $blocks[$b]{PSTART}.

UPDATE: I got them wrong as well. Here is code that works: 

my $position = 1200;
for my $s (@$data) {
    next unless $s->{PROT_NAME} eq 'ALK';
    foreach my $p (0 .. $#{$s->{PDBS}}) {
            foreach my $b (0 .. $#{$s->{PDBS}[$p]->{BLOCKS}}) {
                my @blocks = @{ $s->{PDBS}[$p]->{BLOCKS}};
                if ($position >= $blocks[$b]{PSTART} && $position <= $
+blocks[$b]{PEND} ){
                print ($s->{PDBS}[$p]->{PDB_ID},"\n");}
                        
        }
    }
}

[download]

In reply to Re: json data: dereferencing arrays by hdb
in thread json data: dereferencing arrays by hulketa

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.