Group same values in array using explode or similar method

Question

I have this string :

$a="house1,car1,phone1*house2,car2,phone2*house3,car1,phone3*house4,car3,phone3*";

And i want show in order, the house with the same car, as you can se the element that repeat it´s called "car1"

I want get this :

CAR 1 IN THIS HOUSE
    house1,car1,phone1
    house3,car1,phone3

CAR 2 AND  3 IN HOUSES 2 AND 4   
    house2,car2,phone2
    house4,car3,phone3

As you can see, the car1 repeat in 2 houses with different name, and i want order results in this way

I try do this in many ways, use array_diff, array_unique in foreach loop with explode and array_intersect, and results very bad

If somebody can help me here, thank´s, because i don´t know how i can comparate and show results as i put until

Thank´s in advanced and regards community

Answer 1

Try this (tested in php 5.6):

<?php

// input string
$a="house1,car1,phone1*house2,car2,phone2*house3,car1,phone3*house4,car3,phone3*";

// split on '*' to get tuples
$tuples = explode('*', $a);

// ignore empty tuples (trailing '*' in input string)
$tuples = array_filter($tuples);

// split each tuple on ',' to get individual values
function splitTuples($tuple) {
    return explode(',', $tuple);
}
$tuples = array_map('splitTuples', $tuples);

// sort tuples by the 2nd value
function sortArraysBySecondValue($a, $b) {
    if ($a[1] < $b[1]) {
        return -1;
    }
    if ($a[1] > $b[1]) {
        return 1;
    }
    return 0;
}
usort($tuples, 'sortArraysBySecondValue');

// print tuples
foreach ($tuples as $tuple) {
    echo implode(',', $tuple) . "\n";
}

Output is:

house1,car1,phone1
house3,car1,phone3
house2,car2,phone2
house4,car3,phone3