- URL:https://<geoanalytics-url>/DescribeDataset
- Version Introduced:10.7
Description
The DescribeDataset operation provides an overview of your big data. By default, the tool outputs a table layer containing calculated field statistics and a JSON string outlining geometry and time settings for the input layer.
Optionally, the tool can also output a feature layer representing a sample of your input features or a single polygon feature layer that represents the extent of your input features. You can choose to output one, both, or none.
For example, imagine you are tasked with completing an analysis workflow on a large volume of data. You want to try the workflow, but it could take hours or days with your full dataset. Instead of using time and resources running the full analysis, first create a sample layer to efficiently test your workflow before running it on the full dataset.
Request parameters
Parameter | Details |
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inputLayer (Required) | The table, point, line, or polygon feature layer that will be described, summarized, and sampled. Syntax: As described in Feature input, this parameter can be one of the following:
REST examples
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sampleSize (Optional) | The task will output a feature layer representing a sample of features from the inputLayer. Specify the number of sample features to return. If the input value is null, 0, or empty, no sample layer will be created. The output will have the same schema, geometry, and time type as the input layer. The default is null. REST examples
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extentOutput (Optional) | The task will output a single rectangle feature representing the extent of the inputLayer if this value is set to true. The default is false. Values: true | false REST examples
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outputName (Required) | This value is required when you choose to output an extent feature layer or sample feature layer. The task will create a feature service of the resulting layers. You define the name of the service. REST examples
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context (Optional) | The context parameter contains additional settings that affect task execution. For this task, there are four settings:
Syntax:
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f | The response format. The default response format is html. Values: html | json |
Example usage
Below is a sample request URL for DescribeDataset:
https://hostname.domain.com/webadaptor/rest/services/System/GeoAnalyticsTools/GPServer/DescribeDataset/submitJob?inputLayer={"url":"https://hostname.domain.com/webadaptor/rest/services/Hurricane/hurricaneTrack/0"}&sampleSize=450&extentOutput=true&outputName=myOutput&context={"extent":{"xmin":-122.68,"ymin":45.53,"xmax":-122.45,"ymax":45.6,"spatialReference":{"wkid":4326}}}&f=json
Response
When you submit a request, the service assigns a unique job ID for the transaction.
{
"jobId": "<unique job identifier>",
"jobStatus": "<job status>"
}
After the initial request is submitted, you can use jobId to periodically check the status of the job and messages as described in Check job status. Once the job has successfully completed, use jobId to retrieve the results. To track the status, you can make a request of the following form:
https://<analysis url>/DescribeDataset/jobs/<jobId>
Access results
When the status of the job request is esriJobSucceeded, you can access the results of the analysis by making a request of the following form:
https://<analysis-url>/DescribeDataset/jobs/<jobId>/results/<result type>?token=<your token>&f=json
The DescribeDataset operation has the following result types: outputJSON, output, extentLayer, sampleLayer, and processInfo.
Responses | Description |
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outputJSON | outputJSON returns a JSON that details the properties of the input layer. The following characteristics will be defined in the output JSON:
The result has properties for parameter name, data type, and value. The value property is a JSON that defines general inputLayer characteristics.
See Feature output for more information about how the result layer is accessed. |
output | By default, output will return a table of field statistics. For numeric fields, the following statistics will be calculated:
For date fields, the following statistics will be calculated:
For string fields, the following statistics will be calculated:
The result has properties for parameter name, data type, and value. The contents of value depend on the outputName parameter provided in the initial request. The value contains the URL of the feature service layer.
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extentLayer | Setting extentLayer to true returns a single polygon feature equal to the extent of the input features. Context settings will be used while creating this layer.
The result has properties for parameter name, data type, and value. The contents of value depend on the outputName parameter provided in the initial request. The value contains the URL of the feature service layer.
See Feature output for more information about how the result layer is accessed. |
sampleLayer | sampleLayer returns a subset of the input layer as a feature layer with the same geometry type, time type, and schema as the input. Context settings will be used while creating this output layer. This layer is only output if the sampleSize value is set to 1 or greater.
The result has properties for parameter name, data type, and value. The contents of value depend on the outputName parameter provided in the initial request. The value contains the URL of the feature service layer.
See Feature output for more information about how the result layer is accessed. |
processInfo | The processInfo output contains strings that summarize the Describe Dataset result. These strings are used for reporting by the Describe Dataset tool in the portal's Map Viewer Classic. You can create your own custom reports for your application using these strings. There are four parts in the returned JSON:
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