how to group a multidimensional array using a condition in php? - php

Question

I have the following array
Array
(
[0] => Array
(
[shop] => 3
[price] => 332.00
)
[1] => Array
(
[shop] => 1
[price] => 3335.00
)
[2] => Array
(
[shop] => 3
[price] => 235.00
)
[3] => Array
(
[shop] => 1
[price] => 402.50
)
[4] => Array
(
[shop] => 3
[price] => 332.00
)
)
I need to group using shop and get get the minimum price of each shop in the array.
The expected result is as follows
Array
(
[0] => Array
(
[shop] => 3
[price] => 235.00
)
[1] => Array
(
[shop] => 1
[price] => 402.50
)
)
How will I do it?

Answer 1

You need to use additional variable
<?php
$arr = Array
(
0 => Array
(
'shop' => 3,
'price' => 332.00
),
1 => Array
(
'shop' => 3,
'price' => 232.00
),
2 => Array
(
'shop' => 1,
'price' => 232.00
),
3 => Array
(
'shop' => 3,
'price' => 432.00
),
4 => Array
(
'shop' => 1,
'price' => 132.00
),
);
$filtered = array();
foreach($arr as $prices){
if(FALSE === isset($filtered[$prices['shop']]) || $filtered[$prices['shop']]['price'] > $prices['price']){
$filtered[$prices['shop']] = $prices;
}
}
$filtered = array_values($filtered);
print_r($filtered);
This is very fast example how you can achieve this

Answer 2

It's rather simple.
Create a new array where you will host your stores as keys, and prices as values. What you want to do is to go through each element and first if the key does not exists in your new array, add it and its value. If however the key already exists, check if the current value is lower, and save it if true.
$grouped = [];
foreach ($arr as $k => $v) {
foreach ($k as $key => $value) {
if (isset($grouped[$key])) {
if ($value < $grouped[$key]) {
$grouped[$key] = $value;
}
} else {
$grouped[$key] = $value;
}
}
}
Your new array will look like this (store => price):
[
1 => 402.50,
3 => 235.00
]