Finding and replacing many words - ruby

Question

I frequently need to make many replacements within files. To solve this problem, I have created two files old.text and new.text. The first contains a list of words which must be found. The second contains the list of words which should replace those.
All of my files use UTF-8 and make use of various languages.
I have built this script, which I hoped could do the replacement. First, it reads old.text one line at a time, then replaces the words at that line in input.txt with the corresponding words from the new.text file.
#!/bin/sh
number=1
while read linefromoldwords
do
echo $linefromoldwords
linefromnewwords=$(sed -n '$numberp' new.text)
awk '{gsub(/$linefromoldwords/,$linefromnewwords);print}' input.txt >> output.txt
number=$number+1
echo $number
done < old.text
However, my solution does not work well. When I run the script:
On line 6, the sed command does not know where the $number ends.
The $number variable is changing to "0+1", then "0+1+1", when it should change to "1", then "2".
The line with awk does not appear to be doing anything more than copying the input.txt exactly as is to output.txt.
Do you have any suggestions?
Update:
The marked answer works well, however, I use this script a lot and it takes many hours to finish. So I offer a bounty for a solution which can complete these replacements much quicker. A solution in BASH, Perl, or Python 2 will be okay, provided it is still UTF-8 compatible. If you think some other solution using other software commonly available on Linux systems would be faster, then that might be fine too, so long as huge dependencies are not required.

Answer 1

One line 6, the sed command does not know where the $number ends.
Try quoting the variable with double quotes
linefromnewwords=$(sed -n "$number"p newwords.txt)
The $number variable is changing to "0+1", then "0+1+1", when it should change to "1", then "2".
Do this instead:
number=`expr $number + 1`
The line with awk does not appear to be doing anything more than copying the input.txt exactly as is to output.txt.
awk won't take variables outside its scope. User defined variables in awk needs to be either defined when they are used or predefined in the awk's BEGIN statement. You can include shell variables by using -v option.
Here is a solution in bash that would do what you need.
Bash Solution:
#!/bin/bash
while read -r sub && read -r rep <&3; do
sed -i "s/ "$sub" / "$rep" /g" main.file
done <old.text 3<new.text
This solution reads one line at a time from substitution file and replacement file and performs in-line sed substitution.

Answer 2

Why not to
paste -d/ oldwords.txt newwords.txt |\
sed -e 's#/# / #' -e 's#^#s/ #' -e 's#$# /g#' >/tmp/$$.sed
sed -f /tmp/$$.sed original >changed
rm /tmp/$$.sed
?

Answer 3

I love this kind of questions, so here is my answer:
First for the shake of simplicity, Why not use only a file with source and translation. I mean: (filename changeThis)
hello=Bye dudes
the morNing=next Afternoon
first=last
Then you can define a proper separator in the script. (file replaceWords.sh)
#!/bin/bash
SEP=${1}
REPLACE=${2}
FILE=${3}
while read transline
do
origin=${transline%%${SEP}*}
dest=${transline##*${SEP}}
sed -i "s/${origin}/${dest}/gI" $FILE
done < $REPLACE
Take this example (file changeMe)
Hello, this is me.
I will be there at first time in the morning
Call it with
$ bash replaceWords.sh = changeThis changeMe
And you will get
Bye dudes, this is me.
I will be there at last time in next Afternoon
Take note of the "i" amusement with sed. "-i" means replace in source file, and "I" in s// command means ignore case -a GNU extension, check your sed implementation-
Of course note that a bash while loop is horrendously slower than a python or similar scripting language. Depending on your needs you can do a nested while, one on the source file and one inside looping the translations (changes). Echoing all to stdout for pipe flexibility.
#!/bin/bash
SEP=${1}
TRANSLATION=${2}
FILE=${3}
while read line
do
while read transline
do
origin=${transline%%${SEP}*}
dest=${transline##*${SEP}}
line=$(echo $line | sed "s/${origin}/${dest}/gI")
done < $TRANSLATION
echo $line
done < $FILE

Answer 4

This Python 2 script forms the old words into a single regular expression then substitutes the corresponding new word based on the index of the old word that matched. The old words are matched only if they are distinct. This distinctness is enforced by surrounding the word in r'\b' which is the regular expression word boundary.
Input is from the commandline (their is a commented alternative I used for development in idle). Output is to stdout
The main text is scanned only once in this solution. With the input from Jaypals answer, the output is the same.
#!/bin/env python
import sys, re
def replacer(match):
global new
return new[match.lastindex-1]
if __name__ == '__main__':
fname_old, fname_new, fname_txt = sys.argv[1:4]
#fname_old, fname_new, fname_txt = 'oldwords.txt oldwordreplacements.txt oldwordreplacer.txt'.split()
with file(fname_old) as f:
# Form regular expression that matches old words, grouped in order
old = '(?:' + '|'.join(r'\b(%s)\b' % re.escape(word)
for word in f.read().strip().split()) + ')'
with file(fname_new) as f:
# Ordered list of replacement words
new = [word for word in f.read().strip().split()]
with file(fname_txt) as f:
# input text
txt = f.read()
# Output the new text
print( re.subn(old, replacer, txt)[0] )
I just did some stats on a ~100K byte text file:
Total characters in text: 116413
Total words in text: 17114
Total distinct words in text: 209
Top 10 distinct word occurences in text: 2664 = 15.57%
The text was 250 paragraphs of lorum ipsum generated from here I just took the ten most frequently occuring words and replaced them with the strings ONE to TEN in order.
The Python regexp solution is an order of magnitude faster than the currently selected best solution by Jaypal.
The Python selection will replace words followed by a newline character or by punctuation as well as by any whitespace (including tabs etc).
Someone commented that a C solution would be both simple to create and fastest. Decades ago, some wise Unix fellows observed that this is not usually the case and created scripting tools such as awk to boost productivity. This task is ideal for scripting languages and the technique shown in the Python coukld be replicated in Ruby or Perl.
Paddy.

Answer 5

A general perl solution that I have found to work well for replacing the keys in a map with their associated values is this:
my %map = (
19 => 'A',
20 => 'B',
);
my $key_regex = '(' . join('|', keys %map) . ')';
while (<>) {
s/$key_regex/$map{$1}/g;
print $_;
}
You would have to read your two files into the map first (obviously), but once that is done you only have one pass over each line, and one hash-lookup for every replacement. I've only tried it with relatively small maps (around 1,000 entries), so no guarantees if your map is significantly larger.

Answer 6

At line 6, the sed command does not know where the $number ends.
linefromnewwords=$(sed -n '${number}p' newwords.txt)
I'm not sure about the quoting, but ${number}p will work - maybe "${number}p"
The $number variable is changing to "0+1", then "0+1+1", when it should change to "1", then "2".
Arithmetic integer evaluation in bash can be done with $(( )) and is better than eval (eval=evil).
number=$((number + 1))
In general, I would recommend using one file with
s/ ni3 / nǐ /g
s/ nei3 / neǐ /g
and so on, one sed-command per line, which is imho better to take care about - sort it alphabetically, and use it with:
sed -f translate.sed input > output
So you can always easily compare the mappings.
s/\bni3\b/nǐ/g
might be prefered over blanks as explicit delimiters, because \b:=word boundary matches start/end of line and punctuation characters.

Answer 7

This should reduce the time by some means as this avoids unnecessary loops.
Merge two input files:
Lets assume you have two input files, old.text containing all substitutions and new.text containing all replacements.
We will create a new text file which will act as a sed script to your main file using the following awk one-liner:
awk '{ printf "s/ "$0" /"; getline <"new.text"; print " "$0" /g" }' old.text > merge.text
[jaypal:~/Temp] cat old.text
19
20
[jaypal:~/Temp] cat new.text
A
B
[jaypal:~/Temp] awk '{ printf "s/ "$0" /"; getline <"new.text"; print " "$0" /g" }' old.text > merge.text
[jaypal:~/Temp] cat merge.text
s/ 19 / A /g
s/ 20 / B /g
Note: This formatting of substitution and replacement is based on your requirement of having spaces between the words.
Using merged file as sed script:
Once your merged file has been created, we will use -f option of sed utility.
sed -f merge.text input_file
[jaypal:~/Temp] cat input_file
12 adsflljl
12 hgfahld
12 ash;al
13 a;jfda
13 asldfj
15 ;aljdf
16 a;dlfj
19 adads
19 adfasf
20 aaaadsf
[jaypal:~/Temp] sed -f merge.text input_file
12 adsflljl
12 hgfahld
12 ash;al
13 a;jfda
13 asldfj
15 ;aljdf
16 a;dlfj
A adads
A adfasf
B aaaadsf
You can redirect this into another file using the > operator.

Answer 8

This might work for you:
paste {old,new}words.txt |
sed 's,\(\w*\)\s*\(\w*\),s!\\<\1\\>!\2!g,' |
sed -i -f - text.txt

Answer 9

Here is a Python 2 script that should be both space and time efficient:
import sys
import codecs
import re
sub = dict(zip((line.strip() for line in codecs.open("old.txt", "r", "utf-8")),
(line.strip() for line in codecs.open("new.txt", "r", "utf-8"))))
regexp = re.compile('|'.join(map(lambda item:r"\b" + re.escape(item) + r"\b", sub)))
for line in codecs.open("input.txt", "r", "utf-8"):
result = regexp.sub(lambda match:sub[match.group(0)], line)
sys.stdout.write(result.encode("utf-8"))
Here it is in action:
$ cat old.txt
19
20
$ cat new.txt
A
B
$ cat input.txt
12 adsflljl
12 hgfahld
12 ash;al
13 a;jfda
13 asldfj
15 ;aljdf
16 a;dlfj
19 adads
19 adfasf
20 aaaadsf
$ python convert.py
12 adsflljl
12 hgfahld
12 ash;al
13 a;jfda
13 asldfj
15 ;aljdf
16 a;dlfj
A adads
A adfasf
B aaaadsf
$
EDIT: Hat tip to #Paddy3118 for whitespace handling.

Answer 10

Here's a solution in Perl. It can be simplified if you combined your input word lists into one list: each line containing the map of old and new words.
#!/usr/bin/env perl
# usage:
# replace.pl OLD.txt NEW.txt INPUT.txt >> OUTPUT.txt
use strict;
use warnings;
sub read_words {
my $file = shift;
open my $fh, "<$file" or die "Error reading file: $file; $!\n";
my #words = <$fh>;
chomp #words;
close $fh;
return \#words;
}
sub word_map {
my ($old_words, $new_words) = #_;
if (scalar #$old_words != scalar #$new_words) {
warn "Old and new word lists are not equal in size; using the smaller of the two sizes ...\n";
}
my $list_size = scalar #$old_words;
$list_size = scalar #$new_words if $list_size > scalar #$new_words;
my %map = map { $old_words->[$_] => $new_words->[$_] } 0 .. $list_size - 1;
return \%map;
}
sub build_regex {
my $words = shift;
my $pattern = join "|", sort { length $b <=> length $a } #$words;
return qr/$pattern/;
}
my $old_words = read_words(shift);
my $new_words = read_words(shift);
my $word_map = word_map($old_words, $new_words);
my $old_pattern = build_regex($old_words);
my $input_file = shift;
open my $input, "<$input_file" or die "Error reading input file: $input_file; $!\n";
while (<$input>) {
s/($old_pattern)/$word_map->{$&}/g;
print;
}
close $input;
__END__
Old words file:
$ cat old.txt
19
20
New words file:
$ cat new.txt
A
B
Input file:
$ cat input.txt
12 adsflljl
12 hgfahld
12 ash;al
13 a;jfda
13 asldfj
15 ;aljdf
16 a;dlfj
19 adads
19 adfasf
20 aaaadsf
Create output:
$ perl replace.pl old.txt new.txt input.txt
12 adsflljl
12 hgfahld
12 ash;al
13 a;jfda
13 asldfj
15 ;aljdf
16 a;dlfj
A adads
A adfasf
B aaaadsf

Answer 11

I'm not sure why most of the previous posters insist on using regular-expressions to solve this task, I think this will be faster than most (if not the fastest method).
use warnings;
use strict;
open (my $fh_o, '<', "old.txt");
open (my $fh_n, '<', "new.txt");
my #hay = <>;
my #old = map {s/^\s*(.*?)\s*$/$1/; $_} <$fh_o>;
my #new = map {s/^\s*(.*?)\s*$/$1/; $_} <$fh_n>;
my %r;
; #r{#old} = #new;
print defined $r{$_} ? $r{$_} : $_ for split (
/(\s+)/, "#hay"
);
Use: perl script.pl /file/to/modify, result is printed to stdout.

Answer 12

EDIT - I just noticed that two answers like mine are already here... so you can just disregard mine :)
I believe that this perl script, although not using fancy sed or awk thingies, does the job fairly quick...
I did take the liberty to use another format of old_word to new_word:
the csv format. if it is too complicated to do it let me know and I'll add a script that takes your old.txt,new.txt and builds the csv file.
take it on a run and let me know!
by the way - if any of you perl gurus here can suggest a more perlish way to do something I do here I will love to read the comment:
#! /usr/bin/perl
# getting the user's input
if ($#ARGV == 1)
{
$LUT_file = shift;
$file = shift;
$outfile = $file . ".out.txt";
}
elsif ($#ARGV == 2)
{
$LUT_file = shift;
$file = shift;
$outfile = shift;
}
else { &usage; }
# opening the relevant files
open LUT, "<",$LUT_file or die "can't open $signal_LUT_file for reading!\n : $!";
open FILE,"<",$file or die "can't open $file for reading!\n : $!";
open OUT,">",$outfile or die "can't open $outfile for writing\n :$!";
# getting the lines from the text to be changed and changing them
%word_LUT = ();
WORD_EXT:while (<LUT>)
{
$_ =~ m/(\w+),(\w+)/;
$word_LUT{ $1 } = $2 ;
}
close LUT;
OUTER:while ($line = <FILE>)
{
#words = split(/\s+/,$line);
for( $i = 0; $i <= $#words; $i++)
{
if ( exists ($word_LUT { $words[$i] }) )
{
$words[$i] = $word_LUT { $words[$i] };
}
}
$newline = join(' ',#words);
print "old line - $line\nnewline - $newline\n\n";
print OUT $newline . "\n";
}
# now we have all the signals needed in the swav array, build the file.
close OUT;close FILE;
# Sub Routines
#
#
sub usage(){
print "\n\n\replacer.pl Usage:\n";
print "replacer.pl <LUT file> <Input file> [<out file>]\n\n";
print "<LUT file> - a LookUp Table of words, from the old word to the new one.
\t\t\twith the following csv format:
\t\t\told word,new word\n";
print "<Input file> - the input file\n";
print "<out file> - out file is optional. \nif not entered the default output file will be: <Input file>.out.txt\n\n";
exit;
}