CODEWITHSUNDEEP
phparrays
Greg
Greg

Reputation: 1803

PHP sorting by field?

I have the following array which I populated from MySQL:

print_r ($table);

[0] => Array (
[0] => 67122
[idweather] => 67122
[1] => 2014-09-19 00:04:54   
[date] => 2014-09-19 00:04:54
[2] => 1
[rainfall] => 1
[3] => 10
[windspeed] => 10
[4] => 13.85
[dewpoint] => 13.85  
[5] => 1009.43
[pressure] => 1009.43
[6] => 22.8
[bmp085_temp] => 22.8
[7] => 22.8
[dht22_temp] => 22.8
[8] => 11.58
[abs_hum] => 11.58  
[9] => 45.12
[gust] => 45.12
[10] => 0.18
[uvi] => 0.18
[11] => 97.42
[light] => 97.42
[12] => 57.1
[rel_humidity] => 57.1
[13] =>
[wind_dir] =>
)

This is just [0] - the array contains multiple entries for the day. I would like run multiple sorts so I can get the max rainfall, windspeed, bmp085_temp etc for the day

How do I use the sort like this:

sort($table['wind_dir'];

Not sure if this syntax is right as I get:

PHP Warning:  sort() expects parameter 1 to be array, null given in test.php on line 167

If it helps this is the mysql code:

$sql_array = "select * from weather where date(date) = curdate();";

if(!$result = $db->query($sql_array)){
    die('error running query'); 
}

$table = array();

while ($row = $result->fetch_array()) {
    $table[] = $row;
}

Update:

Ive tried this example: 

usort($table, function($a, $b) {
return $a['dht22_temp'] - $b['dht22_temp'];
});

While it appears to be sorting something its not sorted correctly.

echo $table[0]['dht22_temp'];

Prints out a value but its neither the highest or the lowest :(

Update 2:

Got it working with this:

function compare($a, $b)
 {
  return strnatcmp($a['pressure'], $b['pressure']);
 }
usort($table, 'compare');

Upvotes: 1

Views: 76

Answers (1)

Kevin
Kevin

Reputation: 41873

I suggest use fetch_assoc() in this case. So that in here:

$data = array();
while($row = $result->fetch_assoc()) {
    $data['windspeed'][] = $row['windspeed'];
    $data['rainfall'][] = $row['rainfall'];
}

rsort($data['rainfall']); // reverse descending
$max_rainfall = reset($data['rainfall']); // get the first

Or:

$max_rainfall = max($data['rainfall']);

Upvotes: 1

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