CombineLatest

Category: Combinator

Brief: Combines values from the source sequences whenever any of the sequences have produced an element.

Input: Accepts many input types (single elements, tuples, arrays) as long as at least two are supplied

Output (System.Tuple<input1_type,input2_type,input3_type>): A tuple of inputs

The CombineLatest operator allows you to combine the items emitted by two or more observable sequences. Items are paired whenever any of the sequences emits a new item, using the latest items emitted by each of the other observables.

The first pair is only emitted when all observables have emitted at least one item, so if an observable emits multiple items before the other observables have generated notifications, only the latest of those items will be included in the first pair.

The operator will terminate only when all observable sequences have terminated. If any of the observables terminates early, the last item emitted by that sequence will continue to be used to generate pairs whenever the remaining observables emit new items. This means the resulting sequence will be as long as the longest of the input sequences.

tip

CombineLatest followed by Concat can be used to synchronise multiple source nodes (e.g. CameraCapture at <30 Hz non-triggered frame rates) to the precision of operating system jitter (~10 ms).

tip

CombineLatest can be the reason output files contain duplicate rows. Zip should be used instead. Note that, when applied to multiple video sources, the output frame rate will be the sume of input frame rate. This can be solved by specifying one of the sources as the master, e.g. adding Sample after CombineLatest with the master as secondary input, or using WithLatestFrom instead.