Replacing stopwords based on a list Post: 302939652

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Top Forums UNIX for Dummies Questions & Answers Replacing stopwords based on a list Post 302939652 by drl on Friday 27th of March 2015 11:30:02 AM

03-27-2015

Registered User

Hi.

Here is an alternate solution with perl. The stop words are in a list, one pair to a line, separated by TAB. There is a "general string" which is supplied if no replacement string is specified. This driver script lists the data file, the replacements file, the perl code, and the results:

Code:

#!/usr/bin/env bash

# @(#) s2	Demonstrate easy replacement with perl.

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && . $C perl

FILE=${1-data1}

pl " perl code:"
cat p2

pl " Input data file $FILE:"
cat $FILE

pl " Replacement pairs, old TAB new, unpaired get \"general string\":"
cat replacements.txt

pl " Results:"
./p2 $FILE

exit 0

producing:

Code:

$ ./s2

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian 5.0.8 (lenny, workstation) 
bash GNU bash 3.2.39
perl 5.10.0

-----
 perl code:
#!/usr/bin/env perl

# @(#) p2	Demonstrate replacement from hashed pairs.

use strict;
use warnings;
use Carp;

my ($f);
my $rf = "replacements.txt";
my $gs;    # general string, used if no replacement found.
$gs = "...";

# Read pairs into hash.
my (%hp);
open( $f, "<", $rf ) || croak "cannot open pairs file \"$rf\"";
my ( $t1, $t2 );
while (<$f>) {
  chomp;
  ( $t1, $t2 ) = split( /\s+/, $_, 2 );
  $hp{$t1} = defined($t2) ? $t2 : $gs;
}
close $f;

# Print hash if debugging needed.
# foreach $t1 ( keys %hp ) { print "$t1 => $hp{$t1}\n" };

# Read and replace.
while (<>) {
  foreach $t1 ( keys %hp ) {
    s/$t1/$hp{$t1}/gi;
  }
  print;
}

-----
 Input data file data1:
Now is the time
for all good men
to come to the aid
of their country.
aa aa cc bb cc bb aa AA Aa aA aa

-----
 Replacement pairs, old TAB new, unpaired get "general string":
Now	Then
is	was
good	manly
their	< yours, mine, ours >
aid	bandage
to
aa	xx
bb	yy
cc	zz

-----
 Results:
Then was the time
for all manly men
... come ... the bandage
of < yours, mine, ours > country.
xx xx zz yy zz yy xx xx xx xx xx

If one is interested, there is a perl module https://metacpan.org/release/String-Replace which may be a bit faster (claimed in the object-oriented mode), but I do not think that it allows case insensitivity.

Best wishes ... cheers, drl

drl

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LEARN ABOUT OPENSOLARIS

env

env(1)								   User Commands							    env(1)

NAME

       env - set environment for command invocation

SYNOPSIS

       /usr/bin/env [-i | -] [name=value]... [utility [arg... ]]

       /usr/xpg4/bin/env [-i | -] [name=value]...
	    [utility [arg... ]]

DESCRIPTION

       The  env utility obtains the current environment, modifies it according to its arguments, then invokes the utility named by the utility op-
       erand with the modified environment.

       Optional arguments are passed to utility. If no utility operand is specified, the resulting environment is written to the standard  output,
       with one name=value pair per line.

   /usr/bin
       If env executes commands with arguments, it uses the default shell /usr/bin/sh (see sh(1)).

   /usr/xpg4/bin
       If env executes commands with arguments, it uses /usr/xpg4/bin/sh (see ksh(1)).

OPTIONS

       The following options are supported:

       -i | -	     Ignores  the  environment that would otherwise be inherited from the current shell.  Restricts the environment for utility to
		     that specified by the arguments.

OPERANDS

       The following operands are supported:

       name=value     Arguments of the form name=value modify the execution environment, and are placed  into  the  inherited  environment  before
		      utility is invoked.

       utility	      The  name of the utility to be invoked.  If utility names any of the special shell built-in utilities, the results are unde-
		      fined.

       arg	      A string to pass as an argument for the invoked utility.

EXAMPLES

       Example 1 Invoking utilities with new PATH values

       The following utility:

	 example% env -i PATH=/mybin mygrep xyz myfile

       invokes the utility mygrep with a new PATH value as the only entry in its environment. In this case, PATH is used to locate  mygrep,  which
       then must reside in /mybin.

ENVIRONMENT VARIABLES

       See  environ(5)	for  descriptions of the following environment variables that affect the execution of env: LANG, LC_ALL, LC_CTYPE, LC_MES-
       SAGES, and NLSPATH.

       PATH    Determine the location of the utility. If PATH is specified as a name=value operand to env, the value given shall be  used  in  the
	       search for utility.

EXIT STATUS

       If  utility  is invoked, the exit status of env is the exit status of utility. Otherwise, the env utility returns one of the following exit
       values:

       0	 Successful completion.

       1-125	 An error occurred.

       126	 utility was found but could not be invoked.

       127	 utility could not be found.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

   /usr/bin
       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+
       |CSI			     |enabled			   |
       +-----------------------------+-----------------------------+

   /usr/xpg4/bin
       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWxcu4			   |
       +-----------------------------+-----------------------------+
       |CSI			     |enabled			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ksh(1), sh(1), exec(2), profile(4), attributes(5), environ(5), standards(5)

SunOS 5.11							    2 Jan 2002								    env(1)