I need to calculate the frequency of all values in the array $inputArr
in order to build frequency histogram.
$query="SELECT delay FROM TestDB;";
$result=DatabaseConnector::ExecuteQueryArray($query);
$inputArr = array();
foreach ($result as $row) {
$inputArr[] = array($row['delay']);
}
$freq = array_count_values ($inputArr);
But var_dump($freq)
returns array(0). It's strange, because var_dump($inputArr)
returns the following result (just a sample):
array(429) {
[0]=> array(1) { [0]=> string(1) "0" }
[1]=> array(1) { [0]=> string(1) "0" }
[2]=> array(1) { [0]=> string(1) "0" }
[3]=> array(1) { [0]=> string(1) "9" }
[4]=> array(1) { [0]=> string(2) "12" }
[5]=> array(1) { [0]=> string(1) "7" }
[6]=> array(1) { [0]=> string(2) "15" }
[7]=> array(1) { [0]=> string(1) "3" }
[8]=> array(1) { [0]=> string(2) "13" }
[9]=> array(1) { [0]=> string(1) "0" }
[10]=> array(1) { [0]=> string(1) "1" }
[11]=> array(1) { [0]=> string(2) "35" }
[12]=> array(1) { [0]=> string(2) "24" }
[13]=> array(1) { [0]=> string(2) "14" }
[14]=> array(1) { [0]=> string(1) "4" }
[15]=> array(1) { [0]=> string(1) "0" }
[16]=> array(1) { [0]=> string(2) "26" }
[17]=> array(1) { [0]=> string(1) "0" }
As it can be seen from this output, inputArr
has repeating values, eg 0. So, why $freq = array(0)
?
我会考虑跳过PHP部分,并更改您的SQL语句来为您完成所有工作:
SELECT delay, count(*) AS freq FROM TestDB GROUP BY delay;
$inputArr[] = array($row['delay']);
You are making each element in $inputArr
an array. You don't need a 2d array here, just do:
$inputArr[] = $row['delay'];
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