How to get sum of distinct key -> value in php arrays - php

Question

I have the following string thatI convert into a json array. All I am trying to do put together keys with the same value for id_number and sum the amount to each of these keys and print the resulting value outside the loop.
$response = '{
"nhif":[
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T20:18:50"
},
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T19:59:14"
},
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T09:07:34"
},
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T09:04:27"
},
{
"id_number":"12345678",
"amount":"5",
"date":"2018-09-14T09:04:21"
}
]
}';
$json_response = json_decode($response, true);
//Start NHIF
foreach ($json_response['nhif'] as $nhif) {
echo ''.$nhif{"id_number"}.' '.$nhif{"amount"}.' '.$nhif{"date"}.'<br/>';
}
//END NHIF
My expected output is:
#id_number #amount
AA112233 20
12345678 5
Any workaround this?

Answer 1

You can use array_reduce to sum the amount values by id_number:
$sums = array_reduce($json_response['nhif'], function ($c, $i) {
$c[$i['id_number']] = (isset($c[$i['id_number']]) ? $c[$i['id_number']] : 0) + $i['amount'];
return $c;
}, array());
print_r($sums);
Output:
AA112233 20
12345678 5
Demo on rextester
If you're using PHP7, this
isset($c[$i['id_number']]) ? $c[$i['id_number']] : 0
can be simplified to
$c[$i['id_number']] ?? 0

Answer 2

You can do solve this problem using an array
$response = '{
"nhif":[
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T20:18:50"
},
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T19:59:14"
},
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T09:07:34"
},
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T09:04:27"
},
{
"id_number":"12345678",
"amount":"5",
"date":"2018-09-14T09:04:21"
}
]
}';
$json_response = json_decode($response, true);
$results = array(); // will map the unique keys with it's sum
//Start NHIF
foreach ($json_response['nhif'] as $nhif) {
if(!isset($results[$nhif['id_number']])) // new key initialized
$results[$nhif['id_number']] = $nhif['amount'];
else
$results[$nhif['id_number']] += $nhif['amount'];
}
//END NHIF
foreach($results as $key => $value) {
echo $key .' '.$value; // printing the result
}

Answer 3

Sort the array [If the data is not sorted otherwise do not need to sort].
Do the for loop and summation.
Try with this code sample, there are many other ways to solve this problem depending on problem solving skill.
$response = '{
"nhif":[
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T20:18:50"
},
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T19:59:14"
},
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T09:07:34"
},
{
"id_number":"AA112233",
"amount":"5",
"date":"2018-09-14T09:04:27"
},
{
"id_number":"12345678",
"amount":"5",
"date":"2018-09-14T09:04:21"
}
]
}';
$data = json_decode($response, true);
usort($data['nhif'], function($a, $b) {
return $b['id_number'] <=> $a['id_number'];
});
//Start NHIF
$amount = 0;
$id_number = null;
foreach($data['nhif'] as $nhif) {
if(($nhif['id_number'] != $id_number) && ($id_number != null)){
echo $id_number. "\t". $amount . "<br />";
$id_number = $nhif['id_number'];
$amount = $nhif['amount'];
}
else{
$id_number = $nhif['id_number'];
$amount = $amount + $nhif['amount'];
}
// echo ''.$nhif{"id_number"}.' '.$nhif{"amount"}.' '.$nhif{"date"}.'<br />';
}
echo $id_number. "\t". $amount . "<br />";
//END NHIF

Answer 4

You could create a new array for example $r and check if the key for $nhif['id_number'] already exists.
If it does, add value for $nhif['amount']using +=. If it does not, set the value using =
This example uses the ternary ?: operator:
$r = [];
foreach ($json_response['nhif'] as $nhif) {
isset($r[$nhif['id_number']]) ? $r[$nhif['id_number']] += $nhif['amount'] : $r[$nhif['id_number']] = $nhif['amount'];
}
Demo