# map | select

Projects each element of an observable sequence into a new form by incorporating the element's index. This is an alias for the `select` method.

## Arguments

1. `selector` *(`Function`)*:  Transform function to apply to each source element.  The selector is called with the following information:
   1. the value of the element
   2. the index of the element
   3. the Observable object being subscribed
2. `[thisArg]` *(`Any`)*: Object to use as `this` when executing the predicate.

## Returns

*(`Observable`)*: An observable sequence which results from the comonadic bind operation.

## Example