Reactive-Extensions/RxJS

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doc/api/core/operators/average.md

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# This is RxJS v 4. [Find the latest version here](https://github.com/reactivex/rxjs)
### `Rx.Observable.prototype.average([selector], [thisArg])`
[Ⓢ](https://github.com/Reactive-Extensions/RxJS/blob/master/src/core/linq/observable/average.js "View in source")
 
Computes the average of an observable sequence of values that are in the sequence or obtained by invoking a transform function on each element of the input sequence if present.
 
#### Arguments
1. `[selector]` *(`Function`)*: A transform function to apply to each element.
2. `[thisArg]` *(`Any`)*: Object to use as `this` when executing `selector`.
 
#### Returns
*(`Observable`)*: An observable sequence containing a single element with the average of the sequence of values.
 
#### Example
```js
// Without a selector
var source = Rx.Observable.range(0, 9).average();
 
var subscription = source.subscribe(
function (x) {
console.log('Next: ' + x);
},
function (err) {
console.log('Error: ' + err);
},
function () {
console.log('Completed');
});
 
// => Next: 4
// => Completed
 
// With a selector
var arr = [
{ value: 1 },
{ value: 2 },
{ value: 3 }
];
 
var source = Rx.Observable.from(arr).average(function (x) {
return x.value;
});
 
var subscription = source.subscribe(
function (x) {
console.log('Next: ' + x);
},
function (err) {
console.log('Error: ' + err);
},
function () {
console.log('Completed');
});
 
// => Next: 2
// => Completed
```
 
### Location
 
File:
- [`/src/core/linq/observable/average.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/src/core/linq/observable/average.js)
 
Dist:
- [`rx.all.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.all.js)
- [`rx.all.compat.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.all.js)
- [`rx.aggregates.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.aggregates.js)
 
Prerequisites:
- [`rx.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.js) | [`rx.compat.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.compat.js) | [`rx.lite.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.lite.js) | [`rx.lite.compat.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.lite.compat.js)
 
NPM Packages:
- [`rx`](https://www.npmjs.org/package/rx)
 
NuGet Packages:
- [`RxJS-All`](http://www.nuget.org/packages/RxJS-All/)
- [`RxJS-Aggregates`](http://www.nuget.org/packages/RxJS-Aggregates/)
 
Unit Tests:
- [`/tests/observable/average.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/tests/observable/average.js)