feathr-capabilities.md

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default	Capabilities	Feathr Concepts

Capabilities

Feathr is a scalable platform and below are some of the capabilities it has:

Define Features with Transformation

features = [
    Feature(name="f_trip_distance",                         # Ingest feature data as-is
            feature_type=FLOAT),
    Feature(name="f_is_long_trip_distance",
            feature_type=BOOLEAN,
            transform="cast_float(trip_distance)>30"),      # SQL-like syntax to transform raw data into feature
    Feature(name="f_day_of_week",
            feature_type=INT32,
            transform="dayofweek(lpep_dropoff_datetime)")   # Provides built-in transformation
]

anchor = FeatureAnchor(name="request_features",             # Features anchored on same source
                       source=batch_source,
                       features=features)

Access Features

# Requested features to be joined
# Define the key for your feature
location_id = TypedKey(key_column="DOLocationID",
                       key_column_type=ValueType.INT32,
                       description="location id in NYC",
                       full_name="nyc_taxi.location_id")
feature_query = FeatureQuery(feature_list=["f_location_avg_fare"], key=[location_id])

# Observation dataset settings
settings = ObservationSettings(
  observation_path="abfss://green_tripdata_2020-04.csv",    # Path to your observation data
  event_timestamp_column="lpep_dropoff_datetime",           # Event timestamp field for your data, optional
  timestamp_format="yyyy-MM-dd HH:mm:ss")                   # Event timestamp format， optional

# Prepare training data by joining features to the input (observation) data.
# feature-join.conf and features.conf are detected and used automatically.
feathr_client.get_offline_features(observation_settings=settings,
                                   output_path="abfss://output.avro",
                                   feature_query=feature_query)

Deploy Features to Online (Redis) Store

client = FeathrClient()
redisSink = RedisSink(table_name="nycTaxiDemoFeature")
# Materialize two features into a redis table.
settings = MaterializationSettings("nycTaxiMaterializationJob",
sinks=[redisSink],
feature_names=["f_location_avg_fare", "f_location_max_fare"])
client.materialize_features(settings)

And get features from online store:

# Get features for a locationId (key)
client.get_online_features(feature_table = "agg_features",
                           key = "265",
                           feature_names = ['f_location_avg_fare', 'f_location_max_fare'])
# Batch get for multiple locationIds (keys)
client.multi_get_online_features(feature_table = "agg_features",
                                 key = ["239", "265"],
                                 feature_names = ['f_location_avg_fare', 'f_location_max_fare'])

Define Window Aggregation Features

agg_features = [Feature(name="f_location_avg_fare",
                        key=location_id,                          # Query/join key of the feature(group)
                        feature_type=FLOAT,
                        transform=WindowAggTransformation(        # Window Aggregation transformation
                            agg_expr="cast_float(fare_amount)",
                            agg_func="AVG",                       # Apply average aggregation over the window
                            window="90d")),                       # Over a 90-day window
                ]

agg_anchor = FeatureAnchor(name="aggregationFeatures",
                           source=batch_source,
                           features=agg_features)

Define Named Data Sources

batch_source = HdfsSource(
    name="nycTaxiBatchSource",                              # Source name to enrich your metadata
    path="abfss://green_tripdata_2020-04.csv",              # Path to your data
    event_timestamp_column="lpep_dropoff_datetime",         # Event timestamp for point-in-time correctness
    timestamp_format="yyyy-MM-dd HH:mm:ss")                 # Supports various formats including epoch

Define features on top of other features - Derived Features

# Compute a new feature(a.k.a. derived feature) on top of an existing feature
derived_feature = DerivedFeature(name="f_trip_time_distance",
                                 feature_type=FLOAT,
                                 key=trip_key,
                                 input_features=[f_trip_distance, f_trip_time_duration],
                                 transform="f_trip_distance * f_trip_time_duration")

# Another example to compute embedding similarity
user_embedding = Feature(name="user_embedding", feature_type=DENSE_VECTOR, key=user_key)
item_embedding = Feature(name="item_embedding", feature_type=DENSE_VECTOR, key=item_key)

user_item_similarity = DerivedFeature(name="user_item_similarity",
                                      feature_type=FLOAT,
                                      key=[user_key, item_key],
                                      input_features=[user_embedding, item_embedding],
                                      transform="cosine_similarity(user_embedding, item_embedding)")

Define Streaming Features with Streaming sources such as Kafka

# Define input data schema
schema = AvroJsonSchema(schemaStr="""
{
    "type": "record",
    "name": "DriverTrips",
    "fields": [
        {"name": "driver_id", "type": "long"},
        {"name": "trips_today", "type": "int"},
        {
        "name": "datetime",
        "type": {"type": "long", "logicalType": "timestamp-micros"}
        }
    ]
}
""")
stream_source = KafKaSource(name="kafkaStreamingSource",
                            kafkaConfig=KafkaConfig(brokers=["<replace_with_your_broker>.servicebus.windows.net:9093"],
                                                    topics=["<replace_with_your_eventhub>"],
                                                    schema=schema)
                            )

driver_id = TypedKey(key_column="driver_id",
                     key_column_type=ValueType.INT64,
                     description="driver id",
                     full_name="nyc driver id")

kafkaAnchor = FeatureAnchor(name="kafkaAnchor",
                            source=stream_source,
                            features=[Feature(name="f_modified_streaming_count",
                                              feature_type=INT32,
                                              transform="trips_today + 1",
                                              key=driver_id),
                                      Feature(name="f_modified_streaming_count2",
                                              feature_type=INT32,
                                              transform="trips_today + 2",
                                              key=driver_id)]
                            )