php remove redundant words from string range - php

Question

I have a range of information. For example:
Volume 1 Chapter 3 Page 5 TO Volume 1 Chapter 5 Page 10
what is the fastest way to remove redundant information and convert this to:
Volume 1 Chapter 3 Page 5 TO Chapter 5 Page 10
OR if the input is
Volume 1 Chapter 3 Page 5 TO Volume 1 Chapter 3 Page 10
then output
Volume 1 Chapter 3 Page 5 TO Page 10

Answer 1

The hardest part here is to split the input into tokens, as it's not structured well enough. I used a recursive function to sequentially clean the string of the first element duplicates. It works correctly for this input, but I am not sure, that it's 100% correct, as input structure is unclear:
<?php
$str = 'Volume 1 Chapter 3 Page 5 TO Volume 1 Chapter 3 Page 10';
$str = clear_first_element_duplicates($str);
var_dump($str);
function clear_first_element_duplicates($str)
{
if (preg_match('/(.*?\d)\s(.*)/', $str, $tokens))
{
$regexp = preg_quote($tokens[1]);
$str = preg_replace("/$regexp\s?/", '', $tokens[2]);
return $tokens[1]." ".clear_first_element_duplicates($str);
}
return $str;
}
Prints:
"Volume 1 Chapter 3 Page 5 TO Page 10"

Answer 2

My script seems complex but worth it:
I Added variable Levels, So it's not restricted to just Volume, chapter and pages, you can add for example paragraph line and character if desired, and you can even change the Wording. See examples at the end.
** BE careful with the $separator parameter, it must be Exact(case sensitive) and might appear only once on the script, this is easy to fix but I focused on the important part of the function **
function redundancy($string, $separator){
list($a, $b) = explode($separator, $string);
//getting the numeric values of both sides
$pattern = '/[0-9]+/';
preg_match_all($pattern, $a, $a_values);
preg_match_all($pattern, $b, $b_values);
$a_values = $a_values[0];
$b_values = $b_values[0];
//getting the wording and cleaning out the numbers, I guess this can be improved through a better REGEX
preg_match_all('/\b\w+\b/', $a, $matches);
foreach($matches[0] as $match){
if(!is_numeric($match)) $words[] = $match;
}
//algorithm
$length = count($a_values) - 1; // excluding the last element, to be checked separately
$output = $a.$separator." ";
$same_full_path = true; // check if the levels has been altered to check the last element
$same_parent = true; // check the previous level
for($i = 0; $i < $length; $i++){
if($a_values[$i] !== $b_values[$i] || $same_parent === false){
$same_parent = false;
$same_full_path = false;
$output .= $words[$i]." ".$b_values[$i]." ";
}
}
//adding the word to the last element or not, The last element check must be outside the loop because it's special;
if($same_full_path === false || end($a_values) === end($b_values)) $output .= end($words)." ";
$output .= end($b_values);
echo "$string <Br/> $output; <br/><br/> ";
}
redundancy('Volume 1 Chapter 3 Page 5 TO Volume 1 Chapter 5 Page 10', 'TO');
redundancy('Serie 1 Season 2 Chapter 2 Minute 5 Second 6 Until Serie 1 Season 3 Chapter 4 Minute 3 Second 1', 'Until');
redundancy('District 4 Building 2 Floor 4 Door 5 To District 4 Building 2 Floor 4 Door 8', 'To');
Outputs :
Volume 1 Chapter 3 Page 5 TO Volume 1 Chapter 5 Page 10
Volume 1 Chapter 3 Page 5 TO Chapter 5 Page 10;
-
Serie 1 Season 2 Chapter 2 Minute 5 Second 6 Until Serie 1 Season 3 Chapter 4 Minute 3 Second 1
Serie 1 Season 2 Chapter 2 Minute 5 Second 6 Until Season 3 Chapter 4 Minute 3 Second 1;
-
District 4 Building 2 Floor 4 Door 5 To District 4 Building 2 Floor 4 Door 8
District 4 Building 2 Floor 4 Door 5 To 8;