in reply to sequence of positions to binary sequence

Quick and dirty solution ahead. 
perl -e' @pos=qw(2 4 6 9);
$max=0;
for (0..(@pos -1)){
   $bin[$pos[$_]]=1;
   $max=$pos[$_] if $max<$pos[$_];
}
for (0..$max){
   $bin[$_]=0 unless $bin[$_];
}
print "@bin\n";'

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Update: This assumes that the largest index in @pos is the length of your @bin array, which would work if you only needed to test for true/false on the array, indeed if you only need to test true/false then the second loop is unneeded as undef and 0 are both false ;)

Replies are listed 'Best First'.
Re^2: sequence of positions to binary sequence
by ELISHEVA (Prior) on Apr 16, 2009 at 09:16 UTC

    Thanks to autovivification, the direct calculation of max is unnecessary. To create an array whose final element is at the maximum position of a 1:

    my @bits;
$bits[$_] = 1 for @pos;
for (0..($#bits-1)) {
  $bits[$_]=0 unless defined($bits[$_]);
}

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    Best, beth

[reply]
[d/l]
      Doh!, thanks
[reply]

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