[EMAIL PROTECTED] wrote:
> Help. I'm a frustrated newbie who wants to use Perl to make
> my life easier.
>
> The following simple task is only one small part of a program
> I'm trying to
> put together to automate some things I currently do manually.
>
> I have a file whose format looks like this:
>
> name1 name2 name3
> name4 name5 name6, etc.
>
> The names are separated by spaces. I need the names to be
> one name per
> line, like this:
>
> name1
> name2
> name3, etc.
If the names don't include embedded spaces (i.e. all the whitespace is
delimiters), you can use the default split()
function for this:
while(<>) {
print "$_\n" for split;
}
The perl one-liner for this would be:
$ perl -lne 'print for split' myfile.txt
...
>
> My next Perl task after I get my list of one name per line,
> is to sort the
> list and eliminate duplicate names.
Let's take it step by step. Consider:
@arr = <>;
This reads all the input lines into an array. But we really want to split
each line into the separate names, so we use map for this:
@arr = map split, <>;
Sorting is trivial:
@arr = sort map split, <>;
Eliminating duplicates can be done through a standard trick:
@arr = do { my %seen; grep !$seen{$_}++, sort map split, <> };
Now @arr contains the unique names, in sorted order, ready to print out.
The perl one-liner would be:
perl -le 'print for grep !$seen{$_}++, sort map split, <>' myfile.txt
n.b., moving the sort from where it is to in front of the grep would be more
efficient if the number of duplicates is large.
HTH
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