# Select¶

• Official ReactiveX documentation: Select
Observable.select(selector)

Project each element of an observable sequence into a new form by incorporating the element’s index.

1 - source.map(lambda value: value * value) 2 - source.map(lambda value, index: value * value + index)

Keyword arguments: :param Callable[[Any, Any], Any] selector: A transform function to

apply to each source element; the second parameter of the function represents the index of the source element.
Return type: Observable

Returns an observable sequence whose elements are the result of invoking the transform function on each element of source.