Fill in gaps in an array where a dash appears?

Question

I have a text box that a user can paste a string of comma separated numbers and it puts that into an array. However, in some cases that string may contain numbers separated by a dash and I need to fill in the missing numbers where that dash appears.

Example:

1, 4, 7, 20-25, 31, 46, 100

Needs to become:

1, 4, 7, 20, 21, 22, 23, 24, 25, 31, 46, 100

How might I go about doing this? The gap wont always be 5 numbers and there could be more than one set of dashed numbers in the string that is input.

Grab the input, explode on ",", strip the whitespace. From here you have an array of your numbers. Iterate through them and strpos for any dashes or just explode on "-". That'll give you the starting number and the ending number, fill in the gaps with a for loop. — Chris Rasco, Sep 11 '13 at 19:03

nickb · Accepted Answer · 2013-09-11T19:14:00.253

Here is one way, without a regex:

It is:

Parsing the input string with str_getcsv() to separate it into its individual elements, then trimming whitespace around each element with trim() and array_map().
Iterating over each element, searching for a dash. If it finds a dash, it found a range of numbers, so it separates them into the start and end indexes by explode()ing on the dash, and forms the correct range between $start and $end with range(). It then merges that newly formed range with what has already been formed as the result using array_merge().
If, during iteration, it didn't find a dash, it assumes you have a literal number, and adds just that number to the resulting array.

That's it!

$input = '1, 4, 7, 20-25, 31, 46, 100';
$entries = array_map( 'trim', str_getcsv( $input));

$result = array();
foreach( $entries as $entry) {
    if( strpos( $entry, '-') !== false) {
        list( $start, $end) = explode( '-', $entry);
        $result = array_merge( $result, range( trim($start), trim($end)));
    } else {
        $result[] = $entry;
    }
}

You can see from this demo that it produces:

Array (
    [0] => 1
    [1] => 4
    [2] => 7
    [3] => 20
    [4] => 21
    [5] => 22
    [6] => 23
    [7] => 24
    [8] => 25
    [9] => 31
    [10] => 46
    [11] => 100 )

Edit: To form the resulting string, instead of the array, you just need a call to implode(), like so:

echo implode( ', ', $result);

This will produce:

1, 4, 7, 20, 21, 22, 23, 24, 25, 31, 46, 100

Amal Murali · Answer 2 · 2013-09-11T19:44:10.560

This can be done without the using a regular expression.

Get the user input, explode with , as the delimiter, and you'll get an array of all numbers.
Now use an if statement to check if the string contains a dash.
If it does, explode it again with the delimiter -. Now you'll get two numbers
Use range() to create an array of numbers within that range
Use implode() to join them by a comma.

As a useful function:

Code:

function fill_string_gaps($input) 
{
    $parts = explode(',', $input);
    $resultArray = array();

    foreach ($parts as $part) {
        if(strpos(trim($part), '-')) {
            list($num1, $num2) = explode('-', $part);
            $expanded_num_array = range($num1, $num2);
            $resultArray = array_merge($resultArray, $expanded_num_array);
        } else {
            $resultArray[] = trim($part);
        }        
    }
        $comma_separated = implode(', ', $resultArray);
        return $comma_separated;

}

Usage:

$input = '1, 4, 7, 20-25, 31, 46, 100';
echo fill_string_gaps($input;)

Test cases:

echo fill_string_gaps('1-5');
echo fill_string_gaps('1-5, 12, 24');
echo fill_string_gaps('2, 2, 4, 5-8');

Output:

1, 2, 3, 4, 5
1, 2, 3, 4, 5, 12, 24
2, 2, 4, 5, 6, 7, 8

See it in action!

score 0 · Answer 3 · answered Sep 11 '13 at 19:04

$data = '1, 4, 7, 20-25, 31, 46, 100';
$elts = explode(',', $data);
$res = array();

foreach ($elts as $elt) {
    $elt = trim($elt);

    if (preg_match('/(\d+)-(\d+)/', $elt, $matches) === 1) {
        $res = array_merge($res, range($matches[1], $matches[2]));
    } else {
        $res[] = intval($elt);
    }
}

var_dump($res);

Glavić · Answer 4 · 2013-09-11T19:35:04.417

Simple code :

split string by delimiter , with explode();
remove space from the beginning and end of a string with trim;
function array_map is used so you don't need to do foreach loop just to apply trim() to every element;
create empty array where you will store new elements;
iterate over each number or range with foreach;
do points 1., 2. and 3. again on every iteration;
split string by delimiter - with explode() even if string doesn't have delimiter - in it; result will be array with one or multi elements;
if point 6. has array with multiple elements, that means that there is range involved, so use function range() to create an array containing a range of elements;
store new numbers to point 4. array with array_merge() function;
when point 4. array is full generated; sort values with sort(), so you don't have output like 5, 3, 1, 4 etc. (delete this function if you don't need this functionality);
remove duplicates with array_unique(), so you don't have output like 4, 4, 4, 4, 5 etc. (delete this function if you don't need this functionality)
to convert array back to string like you inputed, use implode() function.

|

function fillGaps($s) {
    $s = array_map('trim', explode(',', $s));
    $ss = [];
    foreach ($s as $n) {
        $n = array_map('trim', explode('-', $n));
        if (count($n) > 1) $n = range($n[0], end($n));
        $ss = array_merge($ss, $n);
    }
    sort($ss); # remove if you don't need sorting
    $ss = array_unique($ss); # remove if duplicates are allowed
    return implode(', ', $ss);
}

Example :

Your example :

echo fillGaps('1,    4, 7, 20   -   25, 31, 46, 100');
# 1, 4, 7, 20, 21, 22, 23, 24, 25, 31, 46, 100

This code will also work for multiple gaps, like :

echo fillGaps('100-105-110');
# 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110

You can even go reverse :

echo fillGaps('10-5');
# 5, 6, 7, 8, 9, 10
# or remove function sort() and output will be 10, 9, 8, 7, 6, 5

Remove duplicates :

echo fillGaps('2-4, 4, 4, 5');
# 2, 3, 4, 5

score 0 · Answer 5 · answered Sep 11 '13 at 19:31

My solution :DEMO HERE

First delete spaces using str_replace()
explode() string using , to array of integers.
explode() every element using - to check if it's a range or just a single integer.
if it's a range , loop using for() or range() and add $i to $newArray , else add the element to $newArray.
implode() using , and print the result.

PHP code :

<?php
       $str=str_replace(' ', '', '1, 4, 7, 20-25, 31, 46, 100');
       $arr = explode(',',$str);
        foreach($arr as $elem){
           $values=explode('-',$elem);
          if(count($values)!=1)  for($i=$values[0];$i<=$values[1];$i++)   $newArr[]=$i;
          else $newArr[]=$elem;
        }
       echo implode(',',$newArr);
?>

OUTPUT:

1,4,7,20,21,22,23,24,25,31,46,100

Fill in gaps in an array where a dash appears?

5 Answers5

Simple code :

Example :