How to remove all elements that satisfy a condition in array in Ruby?

You can use either new_array = array.reject {|x| x < 3} (reject returns a new array) or array.reject! {|x| x < 3} (reject! aka delete_if modifies the array in place).

There’s also the (somewhat more common) select method, which acts like reject except that you specify the condition to keep elements, not to reject them (i.e. to get rid of the elements less than 3, you’d use new_array = array.select {|x| x >= 3}).