mapis an operator which is mapping emitted values to ones we want - it takes value, passes it through given function and returns new Observable.
mapas of a mist which each boat makes a blue boat - it is mapping boat :speedboat: to blue boat.
filteris an operator which emits only those values which satisfy a specified predicate.
mergeflattens multiple Observables together by returning mix of their values into one Observable.
mergemay be understood as a place where two rivers join and make one new river. Boats from both of them will flow on the new river with the order they've entered the river crossing.
combineLatestmultiple Observables to create an Observable whose values are calculated from the latest values of each of its input Observables.
combineLatestas of gallery showing a pair of boats (from different rivers), always the latest ones that entered joined river.
takeLastemits last x values emitted by the source Observable. Which means that if you will call
takeLast(3)it will emit last 3 values emitted by Observable. It will do so after Observable reaching completed state.
takeemits first x values emitted by the source Observable. Which means that if you will call
take(3)it will emit first 3 values emitted by Observable. After that it will complete returned Observable.