Write geoJSON to .json file using php - php

Question

I need to write a new geoJSON feature to a data.json file using php. Right now I'm writing my data to the file like so:
<?php
// Read from json file
$jsondata = json_decode( file_get_contents('data.json') );
// Add the new data
$jsondata []= array(
'measure_location'=> $_POST["measure_location"],
'measure_type'=> $_POST["measure_type"],
'measurement'=> $_POST["measurement"],
'note_text'=> $_POST["note_text"]
);
// encodes the array into a string in JSON format (JSON_PRETTY_PRINT - uses whitespace in json-string, for human readable)
$jsondata = json_encode($jsondata, JSON_PRETTY_PRINT);
// saves the json string in "data.json" (in "dirdata" folder)
// outputs error message if data cannot be saved
if(file_put_contents('data.json', $jsondata));
?>
And this is what the data then looks like in data.json:
{
"measure_location": "52.370611247493486, 4.91587221622467",
"measure_type": "negative",
"measurement": "violence",
"note_text": ""
}
Could I adjust my PHP code to make the data look like so:
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [
"4.91587221622467",
"52.370611247493486"
]
},
"properties": {
"type": "negative",
"input": "violence",
"note": ""
}
}

Answer 1

Got the answer thanks to charlietfl. Changed the php code to:
<?php
// Read from json file
$jsondata = json_decode( file_get_contents('data.json') );
// Add the new data
$jsondata [] = array(
'type' => 'Feature',
'geometry' => array(
'type' => 'Point',
'coordinates' => $_POST["measure_location"],
),
'properties' => array(
'type' => $_POST["measure_type"],
'input' => $_POST["measurement"],
'note' => $_POST["note_text"],
)
);
// encodes the array into a string in JSON format (JSON_PRETTY_PRINT - uses whitespace in json-string, for human readable)
$jsondata = json_encode($jsondata, JSON_PRETTY_PRINT);
// saves the json string in "data.json" (in "dirdata" folder)
// outputs error message if data cannot be saved
if(file_put_contents('data.json', $jsondata));
?>

Answer 2

I cannot the code that works for you. I have tried many times. It produced a wrong format JSON. The correct code should be,
$jsondata -> features [] = array(
'type' => 'Feature',
'geometry' => array(
'type' => 'Point',
'coordinates' => $_POST["measure_location"],
),
'properties' => array(
'type' => $_POST["measure_type"],
'input' => $_POST["measurement"],
'note' => $_POST["note_text"],
)
);