map's best friend is grep, which returns the subset of list elements matching a condition. So you could start by selecting just the array elements you want: grep {substr($_,0,1) ne 'f'} @array

This returns a list consisting of qw(bar baz bodkin), which should be just what you need for your map: my %hash1 = map {getkey($_) => $_} grep {substr($_,0,1) ne 'f'} @array;