array_filter

  • This function’s solution uses a Ruby Hash object since Ruby arrays don’t use associative key/value pairs. See Array for more details.

    Ruby has a real nice way of executing something similar to PHP’s array_filter function. In Ruby we don’t need to create a callback function to execute since we can pass this directly into our method with a block.

    There are two different ways of getting the equivalent of array_filter in Ruby. One for arrays and one for hashes. To perform the equivalent of an array_filter function on an array we use the Enumerable#select method along with a block which represents the callback function we used in PHP.

    PHP

    function short($var) {
   return strlen($var) < 5;
}
 
$colors = array('orange', 'purple', 'red', 'blue');
$result = array_filter($colors, 'short');
var_export($result);
// => array(2 => 'red', 3 => 'blue')

    Ruby

    colors = ['orange', 'purple', 'red', 'blue']
p colors.select {|c| c.length < 5 }
# => ["red", "blue"]

    Performing a filter on collection with associative keys is similar, and we also use Enumerable#select. The result of this method is a little different. Since a hash is not an ordered collection, Ruby returns our results as a nested array instead of key value pairs. We can cast this back to a hash by flattening the results and using Hash.[] to create a hash out of the values.

    PHP

    function short($var) {
   return strlen($var) < 5;
}
$colors = array('a' => 'orange', 'b' => 'blue', 'c' => 'red');
$result = array_filter($colors, 'short');
var_export($result);
// => array('b' => 'blue', 'c' => 'red')

    Ruby

    colors = {:a => 'orange', :b => 'blue', :c => 'red'}
result = colors.select {|key, value| value.length < 5 }
result = Hash[*result.flatten]
# => {:b=>"blue", :c=>"red"}

    see also

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