String to Multidimensional Array with merging and sorting - php

Question

I have this sort of string that come from my database after many use of CONCAT().
1, AA, 6, 10; 1, Z, 1, 5; 2, AE, 1, 5; 2, AF, 6, 10; 3, X, 1, 5; 3, Y, 5, 10
In order to have something clear, let's say this :
The large string is made of multiple substring, all ending by a ;
Each substring is made of four elements :
A first number. Let's call it the Group
A letter or group of letters. They are called the Section
A second number. We will call it From
A third and last number. We will call it To
Using this code
$data = "1, AA, 6, 10; 1, Z, 1, 5; 2, AE, 1, 5; 2, AF, 6, 10; 3, X, 1, 5; 3, Y, 5, 10";
echo $data;
$ret = array_map (
function ($_) {return explode (', ', $_);},
explode (';', $data)
);
I get the following multidimensional array
Array
(
[0] => Array
(
[0] => 1
[1] => AA
[2] => 6
[3] => 10
)
[1] => Array
(
[0] => 1
[1] => Z
[2] => 1
[3] => 5
)
[2] => Array
(
[0] => 2
[1] => AE
[2] => 1
[3] => 5
)
[3] => Array
(
[0] => 2
[1] => AF
[2] => 6
[3] => 10
)
[4] => Array
(
[0] => 3
[1] => X
[2] => 1
[3] => 5
)
[5] => Array
(
[0] => 3
[1] => Y
[2] => 5
[3] => 10
)
)
I want to end with a multidimensional array that looks like that :
Array
(
[0] => Array
(
[0] => 1
[1] => Array
(
[0] => Z
[1] => 1
[2] => 5
)
[2] => Array
(
[0] => AA
[1] => 6
[2] => 10
)
)
[1] => Array
(
[0] => 2
[1] => Array
(
[1] => AE
[2] => 1
[3] => 5
)
[2] => Array
(
[1] => AF
[2] => 6
[3] => 10
)
)
[2] => Array
(
[0] => 3
[1] => Array
(
[1] => X
[2] => 1
[3] => 5
)
[2] => Array
(
[1] => Y
[2] => 6
[3] => 10
)
)
)
I don't know what's the best method to do it in order to get this result nor if it's possible without too complex operations.
What's the best approach to get the final result ? Should I work on the "raw" multidimensional array or should I work from the string from the beginning ?
Merging arrays with same Group
First, I want to merge substring starting with the same Group value. The rest of each string then become another array inside the newly created array.
I think I can do this by parsing the initial array (Or maybe the string itself ?) and pushing the results in a new one, merging the data in the same time.
In my example, it has been done to the six starting arrays that are now grouped into three arrays.
Sorting using the From and To values
After my substrings with the same Group value are combined into arrays, I want to sort these arrays so the To value of a sub-array is always smaller to the From value of the next one.
The initial string are always generated with the following rules :
There will never be overlapping From and To values like that : 1,5 - 4,7. It would be either 1,4 - 5,7 or 1,5 - 6,7
There will never be missing number in a sequence so you will never have something like 1,3 - 5,7
The From and To value of the same array can be the same. So you can get : 1,4 - 5,5 - 6,7
That's why 1, AA, 6, 10; 1, Z, 1, 5; has been sorted to Z, 1, 5 followed AA, 6, 10. Is there a PHP function that can do this kind of sorting (By comparing values with a different key) or should I create my own ?
Also, if you think that I should totally change the way I want to do this (Using multidimensional arrays...) and you have some ideas, go ahead and share them. I'm also here to learn new way to do things.
Edition concerning Database structure
As stated by #deceze, it may be easier to construct my initial string differently during my SQL query. I have tried it but I'm probably not skilled enough to get what I want. My database looks like that :
Database Structure
As you can see, all the rows are linked by a MasterID. This is because I'm doing a 1 to n query on multiple table.
So far, my query looks like that (I removed all the unnecessary stuff from it) :
SELECT s.MasterID,
GROUP_CONCAT(CONCAT( CONCAT( CONCAT( CONCAT( CONCAT(
s2d.Group, ', '),
s2d.Section, ', '),
s2d.From),', '),
s2d.To) SEPARATOR '; ') AS Concatstuff,
FROM table1 AS s
JOIN table2 AS s2d
ON s2d.MasterID = s.MasterID
WHERE MasterID = $MasterID (A PHP variable)
Because of the 1 to N relation, I don't know how to make this differently. Maybe I could keep it simpler and perform two queries instead of one. In the first query, I get the information from table1 and in the second query, the informations from table2.
But if you know a way to do all of that in only one query, I'm eager to learn how you can do this !

Answer 1

I'd recommend modifying your MySQL query before making many PHP changes.
That massive list of concats will grow quite large, eventually you may even need to adjust the MySQL config setting for GROUP_CONCAT() since it'll truncate after a certain length.
Instead, we can keep the GROUP_CONCAT() and group specifically on individual masterid / group combinations with a GROUP BY. Additionally, GROUP_CONCAT() has an ORDER BY attribute which should solve the sorting issue:
SELECT
s.MasterID,
s2d.`group`,
GROUP_CONCAT(
s2d.`section`, ',', s2d.`from`, ',', s2d.`to`
ORDER BY `from`, `to`
SEPARATOR ';'
) AS Concatstuff
FROM
table1 AS s
JOIN table2 AS s2d
ON s2d.MasterID = s.MasterID
GROUP BY
s.MasterID, s2d.`group`
WHERE
s.MasterID = $MasterID;
This should give us data similar to:
MasterID group Concatstuff
2 1 z,1,5;aa,6,10
2 2 ae,1,5;af,6,10
2 3 x,1,5;y,6,10
Assuming you've retrieved this from the database and have it stored in an array named $results, we can iterate over it like:
$final_groups = array();
foreach ($results as $group) {
// your original `array_map()` logic:
$split_group = array_map(function($_) {
return explode(',', $_);
},
explode(';', $group['Concatstuff'])
);
// ... any other processing you want to do
// store the results:
$final_groups[$group['group']] = $split_group;
}
Note: to explicitly answer your question
Is there a PHP function that can do this kind of sorting
Yes, usort():
function sort_group($a, $b) {
// [1] = 'from'
// [2] = 'to'
if ($a[1] == $b[1]) {
if ($a[2] == $b[2]) {
return 0;
}
return ($a[2] < $b[2]) ? -1 : 1;
}
return ($a[1] < $b[1]) ? -1 : 1;
}
usort($split_group, 'sort_group');
You can customize the comparison logic within sort_group() to match whatever you want it to be. Above, I have it sorting on both from and to =]

Answer 2

Trying to give a general answer without writing your code for you:
For each group, you would set use the group number as index for the contained data.
For each group, you will write its group index into the element with index string prefix plus the number zero: $ret1[$group_number]['d0'] = $group_number;. It will get overwritten every time you add stuff to the group.
Then add the group content with some string index appropriate for sorting. I would propose producing an index using sprintf(), like $idx = sprintf('d%05.1f%05.1f', $from, $to);, so the group number will always be sorted ahead. Again here the prefix. Add it with $ret1[$group_number][$idx] = $group_array;.
Once you have completed this for all input data, run over it for sorting and finishing:
Iterate over all groups in $ret1, sort them by keys and remove the keys with array_values(). Add them to a new array with $ret[] = ....