Highlighting array values - php

Question

I have an array of statistics on racing dogs. I need to highlight the maximum and minimum values in each element by adding another element. Let me explain.
Example of array
Array
(
[1] => Array
(
[fast_calc_7] => 31.06
[av_calc_7] => 25.03
)
[2] => Array
(
[fast_calc_7] => 16.74
[av_calc_7] => 18.06
)
[3] => Array
(
[fast_calc_7] => 30.93
[av_calc_7] => 31.06
)
[4] => Array
(
[fast_calc_7] => 29.01
[av_calc_7] => 25.08
)
[5] => Array
(
[fast_calc_7] => 30.72
[av_calc_7] => 31.02
)
[6] => Array
(
[fast_calc_7] => 31.16
[av_calc_7] => 36.02
)
)
Example of resulting array
I need to compare these values and add another element specifying if it is the highest of lowest value. For example, it should generate an array such as the following.
Array
(
[1] => Array
(
[fast_calc_7] => 31.06
[av_calc_7] => 25.03
)
[2] => Array
(
[fast_calc_7] => 16.74
[fast_calc_7_lowest] => TRUE
[av_calc_7] => 18.06
[av_calc_7_lowest] => TRUE
)
[3] => Array
(
[fast_calc_7] => 30.93
[av_calc_7] => 37.06
[av_calc_7_highest] => TRUE
)
[4] => Array
(
[fast_calc_7] => 29.01
[av_calc_7] => 25.08
)
[5] => Array
(
[fast_calc_7] => 30.72
[av_calc_7] => 31.02
)
[6] => Array
(
[fast_calc_7] => 31.16
[fast_calc_7_highest] => TRUE
[av_calc_7] => 36.02
)
)
I'm sure there is a really simple way to do this. The more I have to iterate through arrays, the slower my application gets!
Thanks guys.
EDIT: How data is sourced
JSON array gathered from greyhound website for each dogs "race history"
JSON array is processed to form a nice array for each dogs history with the data for example the time for each race, finishing position etc.
This data is then calculated for each dog to find the fastest time, average time and other data. This is the array above. (Each array is a different dog).
At this point, I need the array processed to add in the highlighting elements.

Answer 1

There isn't much to it. You need to loop over the array, maintaining variables with the indexes of the high/low elements so far for each attribute. After the loop, access those elements and add your extra data.
$lowAverage = $highAverage = array('index' => null, 'value' => 0);
$lowFast = $highFast = array('index' => null, 'value' => 0);
foreach($dogs as $index => $data) {
if($lowAverage['index'] == null || $data['av_calc_7'] < $lowAverage['value']) {
$lowAverage = array('index' => $index, 'value' => $data['av_calc_7']);
}
if($highAverage['index'] == null || $data['av_calc_7'] > $highAverage['value']) {
$highAverage = array('index' => $index, 'value' => $data['av_calc_7']);
}
// same for $lowFast, $highFast
}
if($lowAverage['index'] != null) {
$dogs[$lowAverage['index']]['av_calc_7_lowest'] = true;
}
// same for the other 3 values