filtering operators lambda received lambda received lambda received the first(and last(operators emit only the first and last data item published by the observable the distinct(operator suppresses duplicate items being published by the observable for examplein the following list used as the data for the observablethe numbers and are duplicateduse distinct to suppress duplicates source rx from_list([ ]pipeop distinct(subscribe lambda function source subscribe(lambda valueprint('received'value)howeverwhen the output is generated by the program all duplicates have been suppressedreceived received received received mathematical operators mathematical and aggregate operators perform calculations on the data stream provided by an observable for examplethe rx operators average(operator can be used to calculate the average of set of numbers published by an observable similarly rx operators max(can select the maximum valuerx operators min(the minimum value and rx operators sum(will total all the numbers published etc an example using the rx operators sum(operator is given blowexample of summing all the values in data stream import rx from rx import operators as op set up source and apply sum rx from_list([ ]pipeop sum(subscribe(lambda vprint( )