450 lines
13 KiB
Plaintext
450 lines
13 KiB
Plaintext
[role="xpack"]
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[testenv="platinum"]
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[[evaluate-dfanalytics]]
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=== Evaluate {dfanalytics} API
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[subs="attributes"]
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++++
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<titleabbrev>Evaluate {dfanalytics}</titleabbrev>
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++++
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Evaluates the {dfanalytics} for an annotated index.
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experimental[]
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[[ml-evaluate-dfanalytics-request]]
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==== {api-request-title}
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`POST _ml/data_frame/_evaluate`
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[[ml-evaluate-dfanalytics-prereq]]
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==== {api-prereq-title}
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If the {es} {security-features} are enabled, you must have the following privileges:
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* cluster: `monitor_ml`
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For more information, see <<security-privileges>> and <<built-in-roles>>.
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[[ml-evaluate-dfanalytics-desc]]
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==== {api-description-title}
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The API packages together commonly used evaluation metrics for various types of
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machine learning features. This has been designed for use on indexes created by
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{dfanalytics}. Evaluation requires both a ground truth field and an analytics
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result field to be present.
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[[ml-evaluate-dfanalytics-request-body]]
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==== {api-request-body-title}
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`evaluation`::
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(Required, object) Defines the type of evaluation you want to perform.
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See <<ml-evaluate-dfanalytics-resources>>.
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+
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--
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Available evaluation types:
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* `binary_soft_classification`
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* `regression`
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* `classification`
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--
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`index`::
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(Required, object) Defines the `index` in which the evaluation will be
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performed.
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`query`::
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(Optional, object) A query clause that retrieves a subset of data from the
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source index. See <<query-dsl>>.
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[[ml-evaluate-dfanalytics-resources]]
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==== {dfanalytics-cap} evaluation resources
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[[binary-sc-resources]]
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===== Binary soft classification evaluation objects
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Binary soft classification evaluates the results of an analysis which outputs
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the probability that each document belongs to a certain class. For example, in
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the context of {oldetection}, the analysis outputs the probability whether each
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document is an outlier.
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`actual_field`::
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(Required, string) The field of the `index` which contains the `ground truth`.
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The data type of this field can be boolean or integer. If the data type is
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integer, the value has to be either `0` (false) or `1` (true).
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`predicted_probability_field`::
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(Required, string) The field of the `index` that defines the probability of
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whether the item belongs to the class in question or not. It's the field that
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contains the results of the analysis.
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`metrics`::
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(Optional, object) Specifies the metrics that are used for the evaluation.
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Available metrics:
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`auc_roc`:::
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(Optional, object) The AUC ROC (area under the curve of the receiver
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operating characteristic) score and optionally the curve. Default value is
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{"includes_curve": false}.
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`confusion_matrix`:::
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(Optional, object) Set the different thresholds of the {olscore} at where
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the metrics (`tp` - true positive, `fp` - false positive, `tn` - true
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negative, `fn` - false negative) are calculated. Default value is
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{"at": [0.25, 0.50, 0.75]}.
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`precision`:::
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(Optional, object) Set the different thresholds of the {olscore} at where
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the metric is calculated. Default value is {"at": [0.25, 0.50, 0.75]}.
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`recall`:::
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(Optional, object) Set the different thresholds of the {olscore} at where
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the metric is calculated. Default value is {"at": [0.25, 0.50, 0.75]}.
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[[regression-evaluation-resources]]
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===== {regression-cap} evaluation objects
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{regression-cap} evaluation evaluates the results of a {regression} analysis
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which outputs a prediction of values.
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`actual_field`::
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(Required, string) The field of the `index` which contains the `ground truth`.
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The data type of this field must be numerical.
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`predicted_field`::
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(Required, string) The field in the `index` that contains the predicted value,
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in other words the results of the {regression} analysis.
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`metrics`::
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(Optional, object) Specifies the metrics that are used for the evaluation.
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Available metrics:
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`mean_squared_error`:::
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(Optional, object) Average squared difference between the predicted values and the actual (`ground truth`) value.
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For more information, read https://en.wikipedia.org/wiki/Mean_squared_error[this wiki article].
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`r_squared`:::
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(Optional, object) Proportion of the variance in the dependent variable that is predictable from the independent variables.
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For more information, read https://en.wikipedia.org/wiki/Coefficient_of_determination[this wiki article].
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[[classification-evaluation-resources]]
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==== {classification-cap} evaluation objects
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{classification-cap} evaluation evaluates the results of a {classanalysis} which
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outputs a prediction that identifies to which of the classes each document
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belongs.
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`actual_field`::
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(Required, string) The field of the `index` which contains the `ground truth`.
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The data type of this field must be categorical.
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`predicted_field`::
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(Required, string) The field in the `index` that contains the predicted value,
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in other words the results of the {classanalysis}.
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`metrics`::
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(Optional, object) Specifies the metrics that are used for the evaluation.
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Available metrics:
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`accuracy`:::
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(Optional, object) Accuracy of predictions (per-class and overall).
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`multiclass_confusion_matrix`:::
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(Optional, object) Multiclass confusion matrix.
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`precision`:::
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(Optional, object) Precision of predictions (per-class and average).
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`recall`:::
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(Optional, object) Recall of predictions (per-class and average).
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////
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[[ml-evaluate-dfanalytics-results]]
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==== {api-response-body-title}
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`binary_soft_classification`::
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(object) If you chose to do binary soft classification, the API returns the
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following evaluation metrics:
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`auc_roc`::: TBD
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`confusion_matrix`::: TBD
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`precision`::: TBD
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`recall`::: TBD
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////
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[[ml-evaluate-dfanalytics-example]]
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==== {api-examples-title}
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[[ml-evaluate-binary-soft-class-example]]
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===== Binary soft classification
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[source,console]
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--------------------------------------------------
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POST _ml/data_frame/_evaluate
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{
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"index": "my_analytics_dest_index",
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"evaluation": {
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"binary_soft_classification": {
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"actual_field": "is_outlier",
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"predicted_probability_field": "ml.outlier_score"
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}
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}
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}
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--------------------------------------------------
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// TEST[skip:TBD]
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The API returns the following results:
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[source,console-result]
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----
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{
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"binary_soft_classification": {
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"auc_roc": {
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"score": 0.92584757746414444
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},
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"confusion_matrix": {
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"0.25": {
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"tp": 5,
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"fp": 9,
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"tn": 204,
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"fn": 5
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},
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"0.5": {
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"tp": 1,
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"fp": 5,
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"tn": 208,
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"fn": 9
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},
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"0.75": {
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"tp": 0,
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"fp": 4,
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"tn": 209,
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"fn": 10
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}
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},
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"precision": {
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"0.25": 0.35714285714285715,
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"0.5": 0.16666666666666666,
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"0.75": 0
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},
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"recall": {
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"0.25": 0.5,
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"0.5": 0.1,
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"0.75": 0
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}
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}
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}
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----
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[[ml-evaluate-regression-example]]
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===== {regression-cap}
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[source,console]
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--------------------------------------------------
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POST _ml/data_frame/_evaluate
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{
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"index": "house_price_predictions", <1>
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"query": {
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"bool": {
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"filter": [
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{ "term": { "ml.is_training": false } } <2>
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]
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}
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},
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"evaluation": {
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"regression": {
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"actual_field": "price", <3>
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"predicted_field": "ml.price_prediction", <4>
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"metrics": {
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"r_squared": {},
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"mean_squared_error": {}
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}
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}
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}
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}
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--------------------------------------------------
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// TEST[skip:TBD]
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<1> The output destination index from a {dfanalytics} {reganalysis}.
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<2> In this example, a test/train split (`training_percent`) was defined for the
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{reganalysis}. This query limits evaluation to be performed on the test split
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only.
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<3> The ground truth value for the actual house price. This is required in order
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to evaluate results.
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<4> The predicted value for house price calculated by the {reganalysis}.
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The following example calculates the training error:
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[source,console]
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--------------------------------------------------
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POST _ml/data_frame/_evaluate
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{
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"index": "student_performance_mathematics_reg",
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"query": {
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"term": {
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"ml.is_training": {
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"value": true <1>
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}
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}
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},
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"evaluation": {
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"regression": {
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"actual_field": "G3", <2>
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"predicted_field": "ml.G3_prediction", <3>
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"metrics": {
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"r_squared": {},
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"mean_squared_error": {}
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}
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}
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}
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}
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--------------------------------------------------
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// TEST[skip:TBD]
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<1> In this example, a test/train split (`training_percent`) was defined for the
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{reganalysis}. This query limits evaluation to be performed on the train split
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only. It means that a training error will be calculated.
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<2> The field that contains the ground truth value for the actual student
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performance. This is required in order to evaluate results.
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<3> The field that contains the predicted value for student performance
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calculated by the {reganalysis}.
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The next example calculates the testing error. The only difference compared with
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the previous example is that `ml.is_training` is set to `false` this time, so
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the query excludes the train split from the evaluation.
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[source,console]
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--------------------------------------------------
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POST _ml/data_frame/_evaluate
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{
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"index": "student_performance_mathematics_reg",
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"query": {
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"term": {
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"ml.is_training": {
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"value": false <1>
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}
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}
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},
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"evaluation": {
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"regression": {
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"actual_field": "G3", <2>
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"predicted_field": "ml.G3_prediction", <3>
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"metrics": {
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"r_squared": {},
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"mean_squared_error": {}
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}
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}
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}
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}
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--------------------------------------------------
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// TEST[skip:TBD]
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<1> In this example, a test/train split (`training_percent`) was defined for the
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{reganalysis}. This query limits evaluation to be performed on the test split
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only. It means that a testing error will be calculated.
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<2> The field that contains the ground truth value for the actual student
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performance. This is required in order to evaluate results.
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<3> The field that contains the predicted value for student performance
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calculated by the {reganalysis}.
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[[ml-evaluate-classification-example]]
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===== {classification-cap}
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[source,console]
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--------------------------------------------------
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POST _ml/data_frame/_evaluate
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{
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"index": "animal_classification",
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"evaluation": {
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"classification": { <1>
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"actual_field": "animal_class", <2>
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"predicted_field": "ml.animal_class_prediction", <3>
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"metrics": {
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"multiclass_confusion_matrix" : {} <4>
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}
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}
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}
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}
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--------------------------------------------------
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// TEST[skip:TBD]
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<1> The evaluation type.
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<2> The field that contains the ground truth value for the actual animal
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classification. This is required in order to evaluate results.
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<3> The field that contains the predicted value for animal classification by
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the {classanalysis}.
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<4> Specifies the metric for the evaluation.
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The API returns the following result:
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[source,console-result]
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--------------------------------------------------
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{
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"classification" : {
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"multiclass_confusion_matrix" : {
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"confusion_matrix" : [
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{
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"actual_class" : "cat", <1>
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"actual_class_doc_count" : 12, <2>
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"predicted_classes" : [ <3>
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{
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"predicted_class" : "cat",
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"count" : 12 <4>
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},
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{
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"predicted_class" : "dog",
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"count" : 0 <5>
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}
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],
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"other_predicted_class_doc_count" : 0 <6>
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},
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{
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"actual_class" : "dog",
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"actual_class_doc_count" : 11,
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"predicted_classes" : [
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{
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"predicted_class" : "dog",
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"count" : 7
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},
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{
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"predicted_class" : "cat",
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"count" : 4
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}
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],
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"other_predicted_class_doc_count" : 0
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}
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],
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"other_actual_class_count" : 0
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}
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}
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}
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--------------------------------------------------
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<1> The name of the actual class that the analysis tried to predict.
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<2> The number of documents in the index that belong to the `actual_class`.
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<3> This object contains the list of the predicted classes and the number of
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predictions associated with the class.
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<4> The number of cats in the dataset that are correctly identified as cats.
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<5> The number of cats in the dataset that are incorrectly classified as dogs.
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<6> The number of documents that are classified as a class that is not listed as
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a `predicted_class`.
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