interface SensorRepo {

    fun getSensorParamsLiveData(sensorName: String): LiveData<SensorParams>

    fun getSensorDataLiveData(sensorName: String): LiveData<List<SensorData>>

}

class SomeViewModel(sensorRepo: SensorRepo) : ViewModel() {

    private val sensorNameLiveData = MutableLiveData<String>()

    private val sensorParamsLiveData = Transformations.switchMap(sensorNameLiveData) {
        sensorRepo.getSensorParamsLiveData(it)
    }

    private val sensorDataLiveData = Transformations.switchMap(sensorNameLiveData) {
        sensorRepo.getSensorDataLiveData(it)
    }

    val sensorLiveData: LiveData<Sensor> = MediatorLiveData<Sensor>().apply {

        var lastSensorParams: SensorParams? = null
        var lastSensorData: List<SensorData>? = null

        fun update() {
            val sensorParams = lastSensorParams
            val sensorData = lastSensorData
            if (sensorParams == null || sensorData == null) return

            postValue(Sensor(sensorParams, sensorData))
        }

        addSource(sensorParamsLiveData) { sensorParams ->
            lastSensorParams = sensorParams
            update()
        }

        addSource(sensorDataLiveData) { sensorData ->
            lastSensorData = sensorData
            update()
        }

    }

    data class Sensor(
        val sensorParams: SensorParams,
        val sensorData: List<SensorData>
    )

}

class SomeFragment : Fragment() {

    lateinit var someViewModel: SomeViewModel

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        someViewModel.sensorLiveData.observe(this, Observer { (sensorParams, sensorData) ->
            // consume sensor params and sensor data
        })
    }

}