Re^2: reading binary data from a file

Thank you.

Now, how do I access the 23rd to 35th byte for every row and put it into another array? In Matlab it would be:
new_array = array(:,23:35);
and you're done

Second, how do I access a row and column in that array and put it into a scalar? In Matlab it would be:
scalar = array(3,4)
meaning I'm grabing the 3rd row and 4th column byte.

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Re^3: reading binary data from a file by ikegami (Patriarch) on Oct 29, 2009 at 00:38 UTC
`substr` can be used to extract portions of other strings. It returns a string, though. If you want to treat each character of that string as a byte, you can then use `unpack 'C'`. Square brackets can be used to create anonymous arrays. The contents of the brackets are assigned to the array. The operator returns a reference to the anonymous array. `$array[2][3]` gets the 4th element of the array referenced by the 2nd element of `@array`. perllol All together: `my @recs; while (read($fh, my $rec, 158)) { push @recs, [ unpack 'C', substr($rec, 22, 13) ]; } print $recs[2][3];` [download] Since you're using `unpack` anyway, you can just skip over the unwanted bytes instead of using `substr`. `push @recs, [ unpack 'x22 C13', $rec ];` [download] Update: Ooops, was missing the "*" in the unpack format.	[reply] [d/l] [select]

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Re^3: reading binary data from a file
by ikegami (Patriarch) on Oct 29, 2009 at 00:38 UTC

substr can be used to extract portions of other strings. It returns a string, though. If you want to treat each character of that string as a byte, you can then use unpack 'C*'.

Square brackets can be used to create anonymous arrays. The contents of the brackets are assigned to the array. The operator returns a reference to the anonymous array.

$array[2][3] gets the 4th element of the array referenced by the 2nd element of @array. perllol

All together:

my @recs;
while (read($fh, my $rec, 158)) {
    push @recs, [ unpack 'C*', substr($rec, 22, 13) ];
}

print $recs[2][3];
[download]

Since you're using unpack anyway, you can just skip over the unwanted bytes instead of using substr.

    push @recs, [ unpack 'x22 C13', $rec ];
[download]

Update: Ooops, was missing the "*" in the unpack format.

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