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Create inference trained model API

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Create inference trained model API

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Creates an inference trained model.

This functionality is in technical preview and may be changed or removed in a future release. Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of official GA features.

Request

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PUT _ml/inference/<model_id>

Prerequisites

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If the Elasticsearch security features are enabled, you must have the following built-in roles and privileges:

machine_learning_admin

For more information, see Security privileges and Built-in roles.

Description

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The create inference trained model API enables you to supply a trained model that is not created by data frame analytics.

Path parameters

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<model_id>: (Required, string) The unique identifier of the trained inference model.

Request body

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compressed_definition

(Required, string) The compressed (GZipped and Base64 encoded) inference definition of the model. If compressed_definition is specified, then definition cannot be specified.

definition

(Required, object) The inference definition for the model. If definition is specified, then compressed_definition cannot be specified.

definition.preprocessors: (Optional, object) Collection of preprocessors. See Inference preprocessor definitions for the full list of available preprocessors.
definition.trained_model: (Required, object) The definition of the trained model. See Inference trained model definitions for details.

description

(Optional, string) A human-readable description of the inference trained model.

input

(Required, object) The input field names for the model definition.

input.field_names: (Required, string) An array of input field names for the model.

metadata

(Optional, object) An object map that contains metadata about the model.

tags

(Optional, string) An array of tags to organize the model.

Inference preprocessor definitions

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frequency_encoding

(Required, object) Defines a frequency encoding for a field.

frequency_encoding.field: (Required, string) The field name to encode.
frequency_encoding.feature_name: (Required, string) The name of the resulting feature.
frequency_encoding.frequency_map: (Required, object map of string:double) Object that maps the field value to the frequency encoded value.

one_hot_encoding

(Required, object) Defines a one hot encoding map for a field.

one_hot_encoding.field: (Required, string) The field name to encode.
one_hot_encoding.hot_map: (Required, object map of strings) String map of "field_value: one_hot_column_name".

target_mean_encoding

(Required, object) Defines a target mean encoding for a field.

target_mean_encoding.field: (Required, string) The field name to encode.
target_mean_encoding.feature_name: (Required, string) The name of the resulting feature.
target_mean_encoding.target_map: (Required, object map of string:double) Object that maps the field value to the target mean value.
target_mean_encoding.default_value: (Required, double) The feature value if the field value is not in the target_map.

See Preprocessor examples for more details.

Inference trained model definitions

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tree

(Required, object) The definition for a binary decision tree.

tree.feature_names: (Required, string) Features expected by the tree, in their expected order.
tree.tree_structure: (Required, object) An array of tree_node objects. The nodes must be in ordinal order by their tree_node.node_index value.
tree.classification_labels: (Optional, string) An array of classification labels (used for classification).
tree.target_type: (Required, string) String indicating the model target type; regression or classification.

There are two major types of nodes: leaf nodes and not-leaf nodes.

Leaf nodes only need node_index and leaf_value defined.
All other nodes need split_feature, left_child, right_child, threshold, decision_type, and default_left defined.

tree_node

(Required, object) The definition of a node in a tree.

tree_node.decision_type

(Optional, string) Indicates the positive value (in other words, when to choose the left node) decision type. Supported lt, lte, gt, gte. Defaults to lte.

tree_node.threshold

(Optional, double) The decision threshold with which to compare the feature value.

tree_node.left_child

(Optional, integer) The index of the left child.

tree_node.right_child

(Optional, integer) The index of the right child.

tree_node.default_left

(Optional, boolean) Indicates whether to default to the left when the feature is missing. Defaults to true.

tree_node.split_feature

(Optional, integer) The index of the feature value in the feature array.

tree_node.node_index

(Integer) The index of the current node.

tree_node.split_gain

(Optional, double) The information gain from the split.

tree_node.leaf_value

(Optional, double) The leaf value of the of the node, if the value is a leaf (in other words, no children).

ensemble

(Optional, object) The definition for an ensemble model.

ensemble.feature_names

(Optional, string) Features expected by the ensemble, in their expected order.

ensemble.trained_models

(Required, object) An array of trained_model objects. Supported trained models are tree and ensemble.

ensemble.classification_labels

(Optional, string) An array of classification labels.

ensemble.target_type

(Required, string) String indicating the model target type; regression or classification.

ensemble.aggregate_output

(Required, object) An aggregated output object that defines how to aggregate the outputs of the trained_models. Supported objects are weighted_mode, weighted_sum, and logistic_regression.

See Model examples for more details.

Aggregated output types

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logistic_regression

(Optional, object) This aggregated_output type works with binary classification (classification for values [0, 1]). It multiplies the outputs (in the case of the ensemble model, the inference model values) by the supplied weights. The resulting vector is summed and passed to a sigmoid function. The result of the sigmoid function is considered the probability of class 1 (P_1), consequently, the probability of class 0 is 1 - P_1. The class with the highest probability (either 0 or 1) is then returned. For more information about logistic regression, see this wiki article.

logistic_regression.weights: (Required, double) The weights to multiply by the input values (the inference values of the trained models).

weighted_sum

(Optional, object) This aggregated_output type works with regression. The weighted sum of the input values.

weighted_sum.weights: (Required, double) The weights to multiply by the input values (the inference values of the trained models).

weighted_mode

(Optional, object) This aggregated_output type works with regression or classification. It takes a weighted vote of the input values. The most common input value (taking the weights into account) is returned.

weighted_mode.weights: (Required, double) The weights to multiply by the input values (the inference values of the trained models).

See Aggregated output example for more details.

Examples

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Preprocessor examples

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The example below shows a frequency_encoding preprocessor object:

{
   "frequency_encoding":{
      "field":"FlightDelayType",
      "feature_name":"FlightDelayType_frequency",
      "frequency_map":{
         "Carrier Delay":0.6007414737092798,
         "NAS Delay":0.6007414737092798,
         "Weather Delay":0.024573576178086153,
         "Security Delay":0.02476631010889467,
         "No Delay":0.6007414737092798,
         "Late Aircraft Delay":0.6007414737092798
      }
   }
}

The next example shows a one_hot_encoding preprocessor object:

{
   "one_hot_encoding":{
      "field":"FlightDelayType",
      "hot_map":{
         "Carrier Delay":"FlightDelayType_Carrier Delay",
         "NAS Delay":"FlightDelayType_NAS Delay",
         "No Delay":"FlightDelayType_No Delay",
         "Late Aircraft Delay":"FlightDelayType_Late Aircraft Delay"
      }
   }
}

This example shows a target_mean_encoding preprocessor object:

{
   "target_mean_encoding":{
      "field":"FlightDelayType",
      "feature_name":"FlightDelayType_targetmean",
      "target_map":{
         "Carrier Delay":39.97465788139886,
         "NAS Delay":39.97465788139886,
         "Security Delay":203.171206225681,
         "Weather Delay":187.64705882352948,
         "No Delay":39.97465788139886,
         "Late Aircraft Delay":39.97465788139886
      },
      "default_value":158.17995752420433
   }
}

Model examples

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The first example shows a trained_model object:

{
   "tree":{
      "feature_names":[
         "DistanceKilometers",
         "FlightTimeMin",
         "FlightDelayType_NAS Delay",
         "Origin_targetmean",
         "DestRegion_targetmean",
         "DestCityName_targetmean",
         "OriginAirportID_targetmean",
         "OriginCityName_frequency",
         "DistanceMiles",
         "FlightDelayType_Late Aircraft Delay"
      ],
      "tree_structure":[
         {
            "decision_type":"lt",
            "threshold":9069.33437193022,
            "split_feature":0,
            "split_gain":4112.094574306927,
            "node_index":0,
            "default_left":true,
            "left_child":1,
            "right_child":2
         },
         ...
         {
            "node_index":9,
            "leaf_value":-27.68987349695448
         },
         ...
      ],
      "target_type":"regression"
   }
}

The following example shows an ensemble model object:

"ensemble":{
   "feature_names":[
      ...
   ],
   "trained_models":[
      {
         "tree":{
            "feature_names":[],
            "tree_structure":[
               {
                  "decision_type":"lte",
                  "node_index":0,
                  "leaf_value":47.64069875778043,
                  "default_left":false
               }
            ],
            "target_type":"regression"
         }
      },
      ...
   ],
   "aggregate_output":{
      "weighted_sum":{
         "weights":[
            ...
         ]
      }
   },
   "target_type":"regression"
}

Aggregated output example

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Example of a logistic_regression object:

"aggregate_output" : {
  "logistic_regression" : {
    "weights" : [2.0, 1.0, .5, -1.0, 5.0, 1.0, 1.0]
  }
}

Example of a weighted_sum object:

"aggregate_output" : {
  "weighted_sum" : {
    "weights" : [1.0, -1.0, .5, 1.0, 5.0]
  }
}

Example of a weighted_mode object:

"aggregate_output" : {
  "weighted_mode" : {
    "weights" : [1.0, 1.0, 1.0, 1.0, 1.0]
  }
}

Inference JSON schema

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For the full JSON schema of model inference, click here.

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