averages?

filn

how do i get the average of a group of numbers if the group size is constantly changing?

tsinka

Hi,

how does the code look like ?

Example (using an array):

$arrValues = array(2,5,7,10,12);
$avg = array_sum($arrValues)/count($arrValues);

Thomas

filn

Originally posted by tsinka
Hi,

how does the code look like ?

dont have any code yet. not sure where to begin, because ive run into another problem.

but first, back to the original question..

the numbers come from a database field so as people add review ratings (1 to 5) the database will add more numbers to be averaged.

so what i was thinking i would do (and please correct me if im wrong), would be to just get all the numbers from each review into in big string (ie, 1342543234) where each number is a seperate review, then i was thinking i would have to split that down into each individual number into an array and then i could just add them all together and devide by the total number of array items to get the average.

hows that sound?

tsinka

MySQL ?

laserlight

the numbers come from a database field so as people add review ratings (1 to 5) the database will add more numbers to be averaged.

If you're using some RDMS, then you should be able to write an SQL query to do this for you.

tsinka

How does the table look like ?

Thomas

filn

Originally posted by tsinka
MySQL ?

yes indeed.

filn

Originally posted by tsinka
How does the table look like ?

Thomas

here is the mysql table:

#
# Table structure for table `reviews`
#
# Creation: Oct 29, 2004 at 09:18 PM
# Last update: Oct 29, 2004 at 09:18 PM
#

CREATE TABLE `reviews` (
  `review_id` tinyint(4) NOT NULL default '0',
  `author` varchar(100) NOT NULL default '',
  `email` varchar(100) NOT NULL default '',
  `review` text NOT NULL,
  `rating` tinyint(2) NOT NULL default '0',
  `date` varchar(20) NOT NULL default '',
  PRIMARY KEY  (`review_id`)
) TYPE=MyISAM;

tsinka

To get the avg of all ratings in that table do something like

SELECT AVG(rating) AS avgrating FROM reviews

If you want to get the average ratings grouped by e.g. date:

SELECT date,AVG(rating) AS avgrating FROM reviews GROUP BY date

Thomas