#!perl
use strict;
use warnings;

use Data::Dumper;

my @array = qw/name1 name2 name3 name4 name5/;

my %file = ();

$file{ (split)[0] } = (split)[1] while <DATA>;

my @result = map {
                 $_->[1]
             } sort {
                 $a->[0] cmp $b->[0]
             } map {
                 [ $_, exists $file{$_} ? $file{$_}+0 : 999 ]
             } @array;

print Dumper( \@result );

# output:
#
#$VAR1 = [
#          '4.5',
#          999,
#          '3.4',
#          '-7.9',
#          '6.5'
#        ];

__DATA__
name1   4.5
name3   3.4
name5   6.5
name4   -7.9
name6   3.2