Operators

Creating Observables

Operator	Description
create	Create an Observable from scratch by calling observer methods programmatically.
empty	Creates an Observable that emits no item and completes immediately.
never	Creates an Observable that never completes.
throw	Creates an Observable that terminates with an error.
from_	Convert some other object or data structure into an Observable.
interval	Create an Observable that emits a sequence of integers spaced by a particular time interval.
just	Convert an object or a set of objects into an Observable that emits that object or those objects.
range	Create an Observable that emits a range of sequential integers.
repeat_value	Create an Observable that emits a particular item or sequence of items repeatedly.
start	Create an Observable that emits the return value of a function.
timer	Create an Observable that emits a single item after a given delay.

Transforming Observables

Filtering Observables

Operator	Description
debounce	Only emit an item from an Observable if a particular timespan has passed without it emitting another item.
distinct	Suppress duplicate items emitted by an Observable.
element_at	Emit only item n emitted by an Observable.
filter	Emit only those items from an Observable that pass a predicate test.
first	Emit only the first item, or the first item that meets a condition, from an Observable.
ignore_elements	Do not emit any items from an Observable but mirror its termination notification.
last	Emit only the last item emitted by an Observable.
sample	Emit the most recent item emitted by an Observable within periodic time intervals.
skip	Suppress the first n items emitted by an Observable.
skip_last	Suppress the last n items emitted by an Observable.
take	Emit only the first n items emitted by an Observable.
take_last	Emit only the last n items emitted by an Observable.

Combining Observables

Operator	Description
combine_latest	When an item is emitted by either of two Observables, combine the latest item emitted by each Observable via a specified function and emit items based on the results of this function.
join	Combine items emitted by two Observables whenever an item from one Observable is emitted during a time window defined according to an item emitted by the other Observable.
merge	Combine multiple Observables into one by merging their emissions.
start_with	Emit a specified sequence of items before beginning to emit the items from the source Observable.
switch_latest	Convert an Observable that emits Observables into a single Observable that emits the items emitted by the most-recently-emitted of those Observables.
zip	Combine the emissions of multiple Observables together via a specified function and emit single items for each combination based on the results of this function.
fork_join	Wait for Observables to complete and then combine last values they emitted into a tuple.

Error Handling

Operator	Description
catch	Continues observable sequences which are terminated with an exception by switching over to the next observable sequence.
retry	If a source Observable sends an onError notification, resubscribe to it in the hopes that it will complete without error.

Utility Operators

Operator	Description
delay	Shift the emissions from an Observable forward in time by a particular amount.
do	Register an action to take upon a variety of Observable lifecycle events.
materialize	Materializes the implicit notifications of an observable sequence as explicit notification values.
dematerialize	Dematerializes the explicit notification values of an observable sequence as implicit notifications.
observe_on	Specify the scheduler on which an observer will observe this Observable.
subscribe	Operate upon the emissions and notifications from an Observable.
subscribe_on	Specify the scheduler an Observable should use when it is subscribed to.
time_interval	Convert an Observable that emits items into one that emits indications of the amount of time elapsed between those emissions.
timeout	Mirror the source Observable, but issue an error notification if a particular period of time elapses without any emitted items.
timestamp	Attach a timestamp to each item emitted by an Observable.

Conditional and Boolean Operators

Operator	Description
all	Determine whether all items emitted by an Observable meet some criteria.
amb	Given two or more source Observables, emit all of the items from only the first of these Observables to emit an item.
contains	Determine whether an Observable emits a particular item or not.
default_if_empty	Emit items from the source Observable, or a default item if the source Observable emits nothing.
sequence_equal	Determine whether two Observables emit the same sequence of items.
skip_until	Discard items emitted by an Observable until a second Observable emits an item.
skip_while	Discard items emitted by an Observable until a specified condition becomes false.
take_until	Discard items emitted by an Observable after a second Observable emits an item or terminates.
take_while	Discard items emitted by an Observable after a specified condition becomes false.

Mathematical and Aggregate Operators

Operator	Description
average	Calculates the average of numbers emitted by an Observable and emits this average.
concat	Emit the emissions from two or more Observables without interleaving them.
count	Count the number of items emitted by the source Observable and emit only this value.
max	Determine, and emit, the maximum-valued item emitted by an Observable.
min	Determine, and emit, the minimum-valued item emitted by an Observable.
reduce	Apply a function to each item emitted by an Observable, sequentially, and emit the final value.
sum	Calculate the sum of numbers emitted by an Observable and emit this sum.

Connectable Observable Operators

Operator	Description
connect	Instruct a connectable Observable to begin emitting items to its subscribers.
publish	Convert an ordinary Observable into a connectable Observable.
ref_count	Make a Connectable Observable behave like an ordinary Observable.
replay	Ensure that all observers see the same sequence of emitted items, even if they subscribe after the Observable has begun emitting items.