rx-group_by.hpp File Reference

Return an observable that emits grouped_observables, each of which corresponds to a unique key value and each of which emits those items from the source observable that share that key value. More...

#include "../rx-includes.hpp"

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Classes
struct	rxcpp::member_overload< group_by_tag >

Namespaces
	rxcpp
	rxcpp::operators

Macros
#define	RXCPP_OPERATORS_RX_GROUP_BY_HPP

Functions
template<class... AN>
auto	rxcpp::operators::group_by (AN &&...an) -> operator_factory< group_by_tag, AN... >
	Return an observable that emits grouped_observables, each of which corresponds to a unique key value and each of which emits those items from the source observable that share that key value. More...

Detailed Description

Return an observable that emits grouped_observables, each of which corresponds to a unique key value and each of which emits those items from the source observable that share that key value.

Template Parameters

KeySelector	the type of the key extracting function
MarbleSelector	the type of the element extracting function
BinaryPredicate	the type of the key comparing function

Parameters

ks	a function that extracts the key for each item (optional)
ms	a function that extracts the return element for each item (optional)
p	a function that implements comparison of two keys (optional)

Returns

Observable that emits values of grouped_observable type, each of which corresponds to a unique key value and each of which emits those items from the source observable that share that key value.

Sample Code

bool less(int v1, int v2){
    return v1 < v2;
}

    auto data = rxcpp::observable<>::range(0, 8).
        map([](int v){
            std::stringstream s;
            s << "Value " << v;
            return std::make_pair(v % 3, s.str());
        });
    auto values = data.group_by(
            [](std::pair<int, std::string> v){return v.first;},
            [](std::pair<int, std::string> v){return v.second;},
            less);
    values.
        subscribe(
            [](rxcpp::grouped_observable<int, std::string> g){
                auto key = g.get_key();
                printf("OnNext: key = %d\n", key);
                g.subscribe(
                    [key](const std::string& v){printf("[key %d] OnNext: %s\n", key, v.c_str());},
                    [key](){printf("[key %d] OnCompleted\n", key);});
            },
            [](){printf("OnCompleted\n");});

OnNext: key = 0
[key 0] OnNext: Value 0
OnNext: key = 1
[key 1] OnNext: Value 1
OnNext: key = 2
[key 2] OnNext: Value 2
[key 0] OnNext: Value 3
[key 1] OnNext: Value 4
[key 2] OnNext: Value 5
[key 0] OnNext: Value 6
[key 1] OnNext: Value 7
[key 2] OnNext: Value 8
[key 0] OnCompleted
[key 1] OnCompleted
[key 2] OnCompleted
OnCompleted

Sample Code

    auto values = rxcpp::observable<>::range(0, 8).
        group_by(
            [](int v){return v % 3;},
            [](int v){return 10 * v;});
    values.
        subscribe(
            [](rxcpp::grouped_observable<int, int> g){
                auto key = g.get_key();
                printf("OnNext: key = %d\n", key);
                g.subscribe(
                    [key](int v){printf("[key %d] OnNext: %d\n", key, v);},
                    [key](){printf("[key %d] OnCompleted\n", key);});
            },
            [](){printf("OnCompleted\n");});

OnNext: key = 0
[key 0] OnNext: 0
OnNext: key = 1
[key 1] OnNext: 10
OnNext: key = 2
[key 2] OnNext: 20
[key 0] OnNext: 30
[key 1] OnNext: 40
[key 2] OnNext: 50
[key 0] OnNext: 60
[key 1] OnNext: 70
[key 2] OnNext: 80
[key 0] OnCompleted
[key 1] OnCompleted
[key 2] OnCompleted
OnCompleted

Macro Definition Documentation

#define RXCPP_OPERATORS_RX_GROUP_BY_HPP