in reply to Re^2: Count of patterns in a file without knowing pattern in advance
in thread Count of patterns in a file without knowing pattern in advance

There is usually a "one liner" alternative for simple requirements.

I offer: 

 perl -anE "$h{$F[0]}++}{say qq|$_ appeared $h{$_}| for sort keys %h" 
+*YOUR-FILE*

[download]
Use single quotes if you are on Linux.

                Time is an illusion perpetrated by the manufacturers of space.

  • Comment on Re^3: Count of patterns in a file without knowing pattern in advance
  • Download Code

Replies are listed 'Best First'.
Re^4: Count of patterns in a file without knowing pattern in advance
by roho (Bishop) on Jun 14, 2019 at 13:21 UTC
    Unfortunately, this experimental feature no longer exists in perl version 5.24.1 and forward...produces the following error message:

    "Experimental keys on scalar is now forbidden at -e line 1."

    "It's not how hard you work, it's how much you get done."

[reply]

      Odd - works fine for me:

      $ cat foo
one
two
one
two
three
one
four
$ perl -anE '$h{$F[0]}++}{say qq|$_ appeared $h{$_}| for sort keys %h'
+ foo
four appeared 1
one appeared 3
three appeared 1
two appeared 2
$ perl -v | head -3

This is perl 5, version 26, subversion 1 (v5.26.1) built for x86_64-li
+nux-gnu-thread-multi
(with 62 registered patches, see perl -V for more detail)
$

      [download]

      Are you sure you substituted single quotes as NetWallah advised?

[reply]
[d/l]
      perl -anE "$h{$F[0]}++}{say qq|$_ appeared $h{$_}| for sort keys %h" *YOUR-FILE*
      Unfortunately, this experimental feature no longer exists in perl version 5.24.1 and forward...produces the following error message: "Experimental keys on scalar is now forbidden at -e line 1."

      Are you sure? I don't see that feature being used in this script, did you perhaps make a typo when copying it? (Update: Note the $h vs. %h in the final example below.)

      $ perl -v
This is perl 5, version 28, subversion 1 (v5.28.1) built for x86_64-li
+nux
...

$ cat foo.txt 
one
two
three
one
five
two
ten
one

$ perl -anE '$h{$F[0]}++}{say qq|$_ appeared $h{$_}| for sort keys %h'
+ foo.txt 
five appeared 1
one appeared 3
ten appeared 1
three appeared 1
two appeared 2

$ perl -anE '$h{$F[0]}++}{say qq|$_ appeared $h{$_}| for sort keys $h'
+ foo.txt 
Experimental keys on scalar is now forbidden at -e line 1.
Type of arg 1 to keys must be hash or array (not scalar dereference) a
+t -e line 1, at EOF
Execution of -e aborted due to compilation errors.

      [download]
[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom