1. A method comprising: at a processing apparatus having one or more processors and memory storing one or more programs that, when executed by the one or more processors, cause the respective processing apparatus to perform the method: receiving sensor measurements generated by one or more sensors of one or more devices; pre-classifying the sensor measurements as belonging to one of a plurality of pre-classifications; selecting one or more feature types to extract from the sensor measurements based at least in part on the pre-classification of the sensor measurements, including: in accordance with a determination that the sensor measurements correspond to a first pre-classification, selecting a first set of feature types as the one or more selected feature types; and in accordance with a determination that the set of sensor measurements correspond to a second pre-classification, selecting a second set of feature types as the one or more selected feature types, wherein the first set of feature types is different from the second set of feature types; extracting features of the one or more selected feature types from the sensor measurements, including: in accordance with a determination that the sensor measurements correspond to the first pre-classification, forgoing extracting features of one or more of the second set of feature types while extracting features of the first set of feature types; and in accordance with a determination that the set of sensor measurements correspond to the second pre-classification, forgoing extracting features of one or more of the first set of feature types while extracting features of the second set of feature types; and determining a state of a respective device of the one or more devices in accordance with a classification of the sensor measurements determined based on the one or more features extracted from the sensor measurements.