JSON - Get average from values in php - php

Question

I made a search but no success. I always get some error...
What I want is, get the average of the values "Import" grouped by date.
I appreciate if someone can help me...
My JSON file:
[
{
"Date": "2019-03",
"Import": "200",
"Export": "50"
},
{
"Date": "2019-03",
"Import": "800",
"Export": "200"
},
{
"Date": "2019-04",
"Import": "100",
"Export": "600"
}
]
My PHP Script:
$url = dirname(__DIR__ ) . '/admin/json/all.json';
$json = file_get_contents($url);
$array_origin = json_decode($json, TRUE);
$stack=array();
foreach ($array_origin as $v) {
$stack[$v['Date']]['Import'] = isset($v['Date']) ? $stack[$v['Date']]['Import'] + $v['Import'] : $v['Import'];
$stack[$v['Date']]['Export'] = isset($v['Date']) ? $stack[$v['Date']]['Export'] + $v['Export'] : $v['Export'];
$stack[$v['Date']]['Average_Import'] = 'GET HERE AVERAGE';
}
echo '<pre>' . var_export($stack, true) . '</pre>';
Thanks in advance.
Cheers

Answer 1

What I want is, get the average of the values "Import"
Simple
$array_origin = json_decode('[
{
"Date": "2019-03",
"Import": "200",
"Export": "50"
},
{
"Date": "2019-03",
"Import": "800",
"Export": "200"
},
{
"Date": "2019-04",
"Import": "100",
"Export": "600"
}
]', true);
echo round(array_sum(array_column($array_origin, 'Import'))/count($array_origin));
Output
367
Sandbox
This is an aggregate value of all the rows, so it doesn't make much sense to store it in each of the rows.
If not all rows have the Import you can just make the column a variable and count that instead:
$import = array_column($array_origin, 'Import'); //["200","800","100"]
echo round(array_sum($import)/count($import));
UPDATE
While this wasn't clear
No, because as you see, have a filter "by date". You are printing all itens, not by date. :( –
It's still a trivial problem (once you know how many items there are and the total).
$stack = [];
foreach ($array_origin as $v) {
$key = $v['Date'];
if(!isset($stack[$key])) $stack[$key] = [];
$stack[$key]['Import'] = isset($stack[$key]['Import']) ? $stack[$key]['Import'] + $v['Import'] : $v['Import'];
$stack[$key]['Export'] = isset($stack[$key]['Export']) ? $stack[$key]['Export'] + $v['Export'] : $v['Export'];
//track the number of items
$stack[$key]['items'] = isset($stack[$key]['items'] ) ? ++$stack[$key]['items'] : 1;
$stack[$key]['Average_Import'] = 'GET HERE AVERAGE';
}
//cant average tell you know what they are, this will have to be done after the foreach
array_walk($stack,function(&$item){
$item['Average_Import'] = $item['Export']/$item['items'];
return $item;
});
print_r ($stack);
Output
Array
(
[2019-03] => Array
(
[Import] => 1000
[Export] => 250
[items] => 2
[Average_Import] => 125
)
[2019-04] => Array
(
[Import] => 100
[Export] => 600
[items] => 1
[Average_Import] => 600
)
)
Additionally, this foreach loop was just littered with issues, so I fixed them up. Mostly little things...
For example:
isset($v['Date']) ? $stack[$v['Date']]['Import'] + $v['Import']
This does nothing to prevent read errors from addition, for this value ['Import']. This isset($v['Date']) can be true all day long and that tells us nothing about if $stack[$v['Date']]['Import'] is set or not. If it's not set and we try to read it for addition (have to know its value to add to it) we will get a notice for undefined index.
Sandbox
Now If you don't want to track those item counts ( for whatever reason )
This is a nice trick (plus its fun) to get the number of items for a given date:
$num_dates = array_count_values(array_column($array_origin, 'Date'));
Output
Array
(
[2019-03] => 2
[2019-04] => 1
)
That will give you that information, Then use $num_dates in the callback (literally, pun intended) and the key of the item:
foreach ($array_origin as $v) {
$key = $v['Date'];
if(!isset($stack[$key])) $stack[$key] = [];
$stack[$key]['Import'] = isset($stack[$key]['Import']) ? $stack[$key]['Import'] + $v['Import'] : $v['Import'];
$stack[$key]['Export'] = isset($stack[$key]['Export']) ? $stack[$key]['Export'] + $v['Export'] : $v['Export'];
$stack[$key]['Average_Import'] = 'GET HERE AVERAGE';
}
$num_dates = array_count_values(array_column($array_origin, 'Date'));
array_walk($stack,function(&$item,$key)use($num_dates){
//may want to check if $key exists (but it should always)
$item['Average_Import'] = $item['Export']/$num_dates[$key];
return $item;
});
Output
Array
(
[2019-03] => Array
(
[Import] => 1000
[Export] => 250
[Average_Import] => 125
)
[2019-04] => Array
(
[Import] => 100
[Export] => 600
[Average_Import] => 600
)
)
Sandbox

Answer 2

$array_origin = json_decode('[
{
"Date": "2019-03",
"Import": "200",
"Export": "50"
},
{
"Date": "2019-03",
"Import": "800",
"Export": "200"
},
{
"Date": "2019-04",
"Import": "100",
"Export": "600"
}
]', true);
$counts = [];
$imports = [];
foreach ($array_origin as $data) {
if (isset($data['Import']) && isset($data['Date'])) {
if (!isset($counts[$data['Date']])) {
$counts[$data['Date']] = 0;
$imports[$data['Date']] = 0;
}
$counts[$data['Date']]++;
$imports[$data['Date']] = intval($data['Import']) + $imports[$data['Date']];
}
}
$importAverage = [];
foreach ($imports as $date => $importSum) {
$importAverage[$date] = $importSum > 0 ? $importSum / $counts[$date] : 0;
}
var_dump($importAverage);
array (size=2)
'2019-03' => int 500
'2019-04' => int 100