map{   # map is a way of building a loop
       # map returns a list of the resulting values.
       # this use of map makes no use of the returned list
       # which is often considered bad form, however when
       # golfing it can be useful for shortening your code.
    /(\S+)\s+([\d.]*)/;  # this is a regular expression
                         # (\S+) says to grab 1 or more 
                         # non-white-space characters,

                         # the result captured to $1
                         # \s+ says to grab 1 or more 
                         # white-space characters
                         # ([\d.]*) says to grab either
                         # digits (\d) or a period (.)
                         # 0 or more times.
                         # this will be captured to $2
    $2                   # This is a a ternary operator
                         # A sometimes useful way of   
                         # writing an if-else statement.
                           # This says "if $2"
        ? ( $a{$1} = $2 )  # then set $a{$1} to $2
        : ( $a{$1} = 999 ) # else set $a{$1} to 999
}<FILE>; # the lines read from <FILE> will be used
         # as input to the map, as $_

map{push(@result,$a{$_})}@order;
# again a map, taking the order array and pushing the
# related values from the $a hash into @results
# giving you the ordered numbers.

##</code><code>##

map{/(\S+)\s+(-?[\d.]+)/;$a{$1}=$2?$2:''}<DATA>;
map{push(@result,defined $a{$_} ? $a{$_} : 999)}@order;