extract_distance
This document has been machine translated.
Calculates the distance between each point in the transaction table.
The execution method uses JSON-RPC v2.0.
Example request
extract_distance is a type of analysis API that can be executed by specifying api_method="extract_distance" in the process method of the Provenance API.
The following is an example of starting a provenance session, executing extract_distance, and ending the session.
import xdata_prov.client import Api
api = Api()
api.begin_session()
api.process(api_method="extract_distance", api_params={
"output_ddc": "ddc:jartic_xrain_distances",
"input_ddc": "ddc:jartic_xrain_transaction",
"mesh_ddc": "ddc:jisx0410_mesh5",
"code_column_name": "meshcode",
"distance_method": "geography",
"max_distance": 1000
})
api.commit()
api.end_session()
Parameters
When calling the process method as api_method="extract_distance", api_params takes a dict containing the following keys
The default value, which is blank, is a required parameter.
| Key | Description | Default Value |
|---|---|---|
| output_ddc | registered to ddc | |
| output_mode | output mode (overwrite or error) |
error |
| input_ddc | input data ddc | |
| mesh_ddc | mesh definition ddc | |
| code_column_name | column representing the mesh code in input_ddc | |
| distance_method | distance calculation method (geometry or geography) |
|
| max_distance | upper limit of distance to output to output_ddc |
Input data
Transaction table
The input ddc specified by input_ddc is a "transaction table".
This table must have the following schema
| column name | data type | description |
|---|---|---|
| id | integer | ID to uniquely identify the transaction |
| start_datetime | timestamp with time zone | start datetime |
| end_datetime | timestamp with time zone | end datetime |
| location | geometry | spatial extent |
| (meshcode) | character varying | meshcode |
| * | arbitrary thematic attributes |
| id | integer | ID to uniquely identify the transaction | start_datetime | timestamp with time zone | start_datetime | end_datetime | timestamp with time zone | end_datetime | location | geometry | spatial extent | | (meshcode) | character varying | meshcode | | * | arbitrary thematic attributes |
Normally, transaction tables store the meshcode in the meshcode column.
However, the extract_distance function allows you to specify this column name via the code_column_name parameter.
mesh definition table
The input ddc specified by mesh_ddc is the "mesh definition table".
This table must have the following schema
| column name | data type | description |
|---|---|---|
| code | text | mesh code |
| geom | geometry | area |
| center | geometry | center coordinates |
Note that the geom column is not used by the extract_distance function.
It calculates the distance between the center coordinates indicated by the center column.
Output data
Distance table
A "distance table" is output to the destination ddc specified by output_ddc.
This table has the following schema
| column name | data type | description |
|---|---|---|
| item1 | text | mesh code |
| item2 | text | mesh code |
| distance | double precision | distance between mesh codes |
Return values
extract_distance returns the ddc information of the destination ddc.
This is the behavior defined by the specification of the process method of the Provenance API.