Introduction
Filter
To filter rows from the data frame you can use DataFrame::filter function.
Filter function accepts only one argument which is a ScalarFunction that returns bool value.
Example:
<?php
data_frame()
->read(from_array([
['a' => 100, 'b' => 100],
['a' => 100, 'b' => 200]
]))
->filter(ref('b')->divide(lit(2))->equals(lit('a')))
->write(to_output(false))
->run();
Complex Row-level Filtering
For advanced filtering that requires custom business logic, you can use callback functions:
<?php
use Flow\ETL\Row;
data_frame()
->read($transactionExtractor)
->filter(function(Row $row): bool {
$amount = $row->get('amount')->value();
$type = $row->get('type')->value();
$date = $row->get('date')->value();
// Complex business logic
return $amount > 1000
&& $type === 'purchase'
&& $date > new DateTime('-30 days');
})
->write($highValueTransactionLoader)
->run();
Performance Note: Callback-based filtering cannot be optimized by the engine and should be used sparingly. When possible, prefer built-in scalar functions for better performance.
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