choroba has pointed out bugs in your regular expression (see Metacharacters in perlre). To avoid this sort of mistake, rather than typing all that in, you should consider building a regular expression expression from a list of words, like perhaps: 

      #penghilangan stopword
      my @words = qw(
         untuk
         dari
         di
         yang
         dan
         ini
         itu
         atau
         pada
         ke
         adalah
         setelah
         selalu
         daripada
         dengan
         dalam
         akan
         juga
         tidak
         karena
         tersebut
         ada
         bisa
         sebagai
         sudah
         saat
         oleh
         harus
         menjadi
         secara
         last
         modified
         lebih
         hanya
         para
         telah
         seperti
         sementara
         kepada
         namun
         sangat
         lalu
         belum
         bagi
         tak
         kalau
         bahwa
         tetapi
         dapat
         antara
         banyak
         kembali
         saja
         atas
         hingga
         melalui
         terjadi
         tapi
         sampai
         tentang
         sama
         agar
         memang
         lagi
         selama
         mencapai
         terus
         yakni
         the
         terhadap
         ketika
         merupakan
         sehingga
         sebuah
         jika
         bukan
         jadi
         sejumlah
         sejak
         perlu
         mulai
         jelas
         pun
         masih
         mengatakan
         menurut
         sekitar
         lain
         melakukan
         baru
         beberapa
         hal
      );
      my $regex = join '|', map qr/\b\Q$_\E\b/, @words;
      $kata =~ s/$regex//g;

[download]

Other changes you might consider include:

  1. strict and warnings are good. See Use strict warnings and diagnostics or die.
  2. A more natural way of expressing $#ARGV + 1 != 1 might be @ARGV != 1
  3. Your second $kata =~ tr/[A-Z]/[a-z]/; is unnecessary, since you already lower-cased everything when building %freq.
  4. You have a whole bunch of substitutions for removing characters. Looking at them, I wonder if you really mean what you have written. For example, do you really want to remove the three character sequence "`”, or do you mean remove any occurrence of these three characters? (The escape before " is unnecessary) I think you would probably get your actual desired result replacing $kata =~ s/\d+//g;, $kata =~ s/[!.,()*]|\"`”//g; and $kata =~ s/-+//g; with $kata =~ s/[\d!.,()*"`”\-+]//g;

Update: Corrected oversight in replacement RE in 4. Thanks choroba.

#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

In reply to Re: how to create word list from input text file by kennethk
in thread read whole file in a directory by ask91

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