The easiest thing to do would be to just create a little utility function that optionally prints each metric if it is defined:
<?php
function print_if_not_empty(array &$arr, $key, $suffix = '') {
if (!empty($arr[$key])) {
echo $arr[$key] . ' ' . $suffix . '<br />';
}
}
And then you would call it like this:
print_if_not_empty($data, 'Engine Displacement 1', "liters");
print_if_not_empty($data, 'Engine Displacement 2', "cc's");
print_if_not_empty($data, 'Engine Displacement 3', "ci's");
print_if_not_empty($data, 'Engine Size', "cylinders");
print_if_not_empty($data, 'Horsepower', "hp");
print_if_not_empty($data, 'Kilowatts', "kw");
print_if_not_empty($data, 'Engine Manufacturer');
print_if_not_empty($data, 'Engine Model');
print_if_not_empty($data, 'Primary Fuel Type');
print_if_not_empty($data, 'Secondary Fuel Type');
echo '<br/>';
The print_if_not_empty
function takes an array, a key into that array, and an optional suffix. It checks to make sure that the key exists in the array and that it is not empty, and if so it prints the value with the specified suffix. If it’s not in the array or it is and it is empty, it prints nothing.