PHP Extract and count first elements of each element in multidimensional array - php

Question

I have this array in php,
$mainArray = array(
array("apple","two", "grren"),
array("samsung","five", "red"),
array("microsoft","one","gray"),
array("apple","nine", "blue"),
array("samsung","ten", "white"),
array("nokia","seven", "yellow")
);
I can easily loop through it and extract all the first entries of each array like this:
foreach($mainArray as $w => $n) {
$whatever = $mainArray[$w][0];
}
I'm trying to count how many entries are the same in the first element of each array, and have a result of something like:
apple (2)
samsung (2)
microsoft (1)
nokia (1)
I'm just not sure what is the correct way to do this.
Thank you in advance.

Answer 1

print_r(
array_count_values(
array_map('array_shift', $mainArray)
)
);
Output (Demo):
Array
(
[apple] => 2
[samsung] => 2
[microsoft] => 1
[nokia] => 1
)
So even I am a big fan of foreach, why did I not use it here?
First of all, to count values in an array, in PHP we have array_count_values. It does the job for us.
So the only problem left was to get all the first items into an array to count them with array_count_values. That is a typical mapping job, and I like mapping, too, next to foreach so I tried if array_map together with array_shift worked - and it did.
However you might want to look for a function called array_column. It's not yet available with PHP itself, but as PHP code in another answer:
$counts = array_count_values(array_column($mainArray, 0));

Answer 2

$count = array();
foreach($mainArray as $array) {
$first = $array[0];
if(!isset($count[$first])) $count[$first] = 0;
$count[$first]++;
}
print_r($count);

Answer 3

Collect every first element of the deep arrays by pushing them into a new array ($result in my example) and then call array_count_values() on that array. Like so:
$mainArray = array(
array("apple","two", "grren"),
array("samsung","five", "red"),
array("microsoft","one","gray"),
array("apple","nine", "blue"),
array("samsung","ten", "white"),
array("nokia","seven", "yellow")
);
$result = array();
foreach( $mainArray as $k => $v )
{
// let's continue if $v is not an array or is empty
if( !is_array( $v ) || empty( $v ) ) continue;
$result[] = $v[ 0 ];
}
var_dump( array_count_values( $result ) );

Answer 4

You can loop through the $mainArray to build a full array/list of values and then use array_count_values() on that:
$firstElements = array();
foreach ($mainArray as $arr) {
$firstElements[] = $arr[0];
}
$counts = array_count_values($firstElements);
Another option would be to loop through $mainArray and insert the value as an index for an array (if it doesn't already exist) and then increment it each time (this will do the same thing as array_count_values() in the end):
$counts = array();
foreach ($mainArray as $arr) {
if (!isset($counts[$arr[0]])) $counts[$arr[0]] = 0;
$counts[$arr[0]]++;
}

Answer 5

You can do it just like this:
foreach($mainArray as $n) {
$count[$n[0]] = isset($count[$n[0]]) ? $count[$n[0]]++ : 1;
}
var_dump($count); //should give you something like
/*
array(4) {
["apple"]=>
int(2)
["samsung"]=>
int(2)
["microsoft"]=>
int(1)
["nokia"]=>
int(1)
}
*/