Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 515
  • Last Modified:

PHP; Calculate Standard Deviation and Mean from Dreamweaver Recordset

Would like to calculate the mean and standard deviation from the 'id' field of a simple Dreamweaver Recordset which is:

mysql_select_db($database_conn_latestmysql, $conn_latestmysql);
$query_rst_price1 = "SELECT id FROM latest_ctry";
$rst_price1 = mysql_query($query_rst_price1, $conn_latestmysql) or  die(mysql_error());
$row_rst_price1 = mysql_fetch_assoc($rst_price1);
$totalRows_rst_price1 = mysql_num_rows($rst_price1);

Two difficulties:
1. correctly creating the array from the recordset
2. using the function sd($array).

Could anyone please help?
0
tweddlewalker
Asked:
tweddlewalker
  • 2
1 Solution
 
Ray PaseurCommented:
Do you have the function sd() code written yet?  If not, check this page.  It may or may not be part of your PHP installation.
http://php.net/manual/en/function.stats-standard-deviation.php

This should help get things started.

error_reporting(E_ALL);
mysql_select_db($database_conn_latestmysql, $conn_latestmysql);
$query_rst_price1 = "SELECT id FROM latest_ctry";
$rst_price1 = mysql_query($query_rst_price1) or  die(mysql_error());

// NUMBER OF ROWS
$num = mysql_num_rows($rst_price1);

// COLLECT THE ID FROM EACH ROW
$ids = array();
while ($row = mysql_fetch_object($rst_price1))
{
    $ids[] = $row->id;
}

// COMPUTATIONS HERE
$sum = array_sum($ids);
$avg = $sum / $num;

Open in new window

0
 
tweddlewalkerAuthor Commented:
Thank you for your help. It has unlocked the problem. Due to inexperience had omitted the line:
$ids[] = $row->id;

Now we can write:
  //calculate the variance
$the_variance = 0.0;
  for ($i = 0; $i < $num; $i++)
  {
    //sum the array
    $the_variance = $the_variance + ($ids[$i] - $idsvg) * ($ids[$i] - $idsvg);
  }
  $the_variance =$the_variance /$num-1;
  //now get the standard deviation
  $sd=sqrt($the_variance)

to complete the sequence and it works.
First rate
0
 
Ray PaseurCommented:
Excellent!  Thanks for the points, ~Ray
0

Featured Post

Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now