Doh! I must have taken some "stupid" pills with breakfast today :-(

However, that map chomp, <$in1>; will result in a load of '1's being emitted to the grep denoting the success of the chomps. The whole line should perhaps be

my @data1 = grep length, map {chomp; $_} <$in1>;
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Obviously, your original line was fine and I'm sorry my buffle-headed senior moment got us into this :-/

Cheers,

JohnGG