stream predicate

A stream predicate is a condition or rule used to filter or select specific elements from a stream of data. It is typically used in programming languages that support functional programming paradigms, such as Java's Stream API or Python's filter function.

By applying a predicate to a stream, you can specify the criteria that an element must meet in order to be included in the resulting stream. The predicate is usually expressed as a lambda function or a method reference, which takes an input element and returns true or false based on the condition.

For example, suppose you have a stream of numbers and you want to filter out only the even numbers. You can use a stream predicate to achieve this:

Java example using Stream API:

List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
List<Integer> evenNumbers = numbers.stream()
                                  .filter(n -> n % 2 == 0)
                                  .collect(Collectors.toList());

Python example using filter function:

numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
even_numbers = list(filter(lambda n: n % 2 == 0, numbers))

In both examples, the stream predicate (`n -> n % 2 == 0` in Java and `lambda n: n % 2 == 0` in Python) specifies the condition for selecting even numbers from the stream. The resulting `evenNumbers` or `even_numbers` list will only contain the filtered elements.

I hope this helps! Let me know if you have any more questions.