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Appendix K: Geographic functions

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Appendix K: Geographic functions

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The geographic functions detect anomalies in the geographic location of the input data.

The machine learning features include the following geographic function: lat_long.

You cannot create forecasts for anomaly detection jobs that contain geographic functions. You also cannot add rules with conditions to detectors that use geographic functions.

Lat_long

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The lat_long function detects anomalies in the geographic location of the input data.

This function supports the following properties:

  • field_name (required)
  • by_field_name (optional)
  • over_field_name (optional)
  • partition_field_name (optional)

For more information about those properties, see the create anomaly detection jobs API.

Example 1: Analyzing transactions with the lat_long function.

PUT _ml/anomaly_detectors/example1
{
  "analysis_config": {
    "detectors": [{
      "function" : "lat_long",
      "field_name" : "transaction_coordinates",
      "by_field_name" : "credit_card_number"
    }]
  },
  "data_description": {
    "time_field":"timestamp",
    "time_format": "epoch_ms"
  }
}

If you use this lat_long function in a detector in your anomaly detection job, it detects anomalies where the geographic location of a credit card transaction is unusual for a particular customer’s credit card. An anomaly might indicate fraud.

A "typical" value indicates a centroid of a cluster of previously observed locations that is closest to the "actual" location at that time. For example, there may be one centroid near the person’s home that is associated with the cluster of local grocery stores and restaurants, and another centroid near the person’s work associated with the cluster of lunch and coffee places.

The field_name that you supply must be a single string that contains two comma-separated numbers of the form latitude,longitude, a geo_point field, a geo_shape field that contains point values, or a geo_centroid aggregation. The latitude and longitude must be in the range -180 to 180 and represent a point on the surface of the Earth.

For example, JSON data might contain the following transaction coordinates:

{
  "time": 1460464275,
  "transaction_coordinates": "40.7,-74.0",
  "credit_card_number": "1234123412341234"
}

In Elasticsearch, location data is likely to be stored in geo_point fields. For more information, see geo_point data type. This data type is supported natively in machine learning features. Specifically, when pulling data from a geo_point field, a datafeed will transform the data into the appropriate lat,lon string format before sending to the anomaly detection job.

For more information, see Altering data in your datafeed with runtime fields.

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