Created
February 24, 2012 15:19
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Calculate Percentage Change
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<? | |
/** | |
Calculates the percentage change between two numbers. | |
Useful for showing how much traffic has changed from one time period to the next. | |
*/ | |
$percentChange = function ($cur, $prev) { | |
if ($cur == 0) { | |
if ($prev == 0) { | |
return array('diff' => 0, 'trend' => ''); | |
} | |
return array('diff' => -($prev * 100), 'trend' => 'down_arrow'); | |
} | |
if ($prev == 0) { | |
return array('diff' => $cur * 100, 'trend' => 'up_arrow'); | |
} | |
$difference = ($cur - $prev) / $prev * 100; | |
$trend = ''; | |
if ($cur > $prev) { | |
$trend = 'up_arrow'; | |
} else if ($cur < $prev) { | |
$trend = 'down_arrow'; | |
} | |
return array('diff' => round($difference, 0), 'trend' => $trend); | |
}; | |
### TESTS ### | |
# Decreasing | |
print_r($percentChange(2, 7)); print "\n"; | |
# Increasing | |
print_r($percentChange(7, 3)); print "\n"; | |
# Increasing | |
print_r($percentChange(7, 0)); print "\n"; | |
# Decreasing | |
print_r($percentChange(0, 2)); print "\n"; | |
# No change | |
print_r($percentChange(0, 0)); print "\n"; | |
?> |
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