This tool provides basic spatial functions for processing a CSV files with WKT geometries. You can calculate interesection, buffer, bounding box, area, dissolve, difference and so on. It is build on top of Spatialite and thanks to it has very low memory footprint and it is even ready for large datasets (millions of rows). This tool could be handy if you dont have PostGIS or similar tools available.
SpatialUtils is CSV based (input and output). There are some requirements for geometries:
- Geometry has to be stored as WKT string (https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry).
- Coordinate system of geometry has to be 4326 (WGS84).
If your data is in other format than CSV with WKT (e.g. Shapefile, GeoJSON), you can convert it using for example ogr2ogr utility (https://gdal.org/drivers/vector/csv.html).
Spatial functions
You can use one of the following spatial function in each execution of SpatialUtils:
- area
- computes area in square meters for each polygon
- value for
function
parameter in configuration isarea
- bounding box
- computes x_min, x_max, y_min and y_max for each geometry
- value for
function
parameter in configuration isbbox
- buffer
- computes buffer around geometry (point, line, polygon) with defined radius in meters
- value for
function
parameter in configuration isbuffer
- centroid
- computes a centroid point for each geometry
- value for
function
parameter in configuration iscentroid
- dissolve
- computes an union of geometries based on same values of attribute key
- value for
function
parameter in configuration isdissolve
- intersection
- computes an intersection between geometries from two input tables
- value for
function
parameter in configuration isintersection
- isvalid
- validates WKT geometries and writes result into a two new columns -
isvalid
andisvalid_reason
- value for
function
parameter in configuration isisvalid
- validates WKT geometries and writes result into a two new columns -
You can check for example https://postgis.net/workshops/postgis-intro/geometry_returning.html for further information about spatial functions.
Installation
SpatialUtils is available as Keboola Connection Component and it is available to registered Keboola users. You have to be logged in your Keboola project (https://connection.keboola.com) to use it. To open SpatialUtils just go to Applications, choose New Application and write "SpatialUtils" into the search bar. Then choose CleverAnalytics SpatialUtils.
Configuration
With the SpatialUtils application opened, choose New Configuration and fill in the form.
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Secondly you need to pass a configuration JSON into SpatialUtils. Please check the examples below to get the idea how the configuration file should look.
Code Block |
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{ "function": "area", "in_csv": { "wkt_column_name": "geom", "out_columns": [ "zone_id" ] } } |
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Code Block |
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{ "function": "intersection", "in_left_csv": { "filename": "/workdir/orders.csv", "wkt_column": "geom", "join_column": "restaurant_id", "out_columns": [ "order_id", "restaurant_id" ] }, "in_right_csv": { "filename": "/workdir/zones.csv", "wkt_column": "geom", "join_column": "zone_id", "out_columns": [ "zone_id", "restaurant_id" ] } } |
Additional info:
- Parameter
join_column
is optional. If specified than left and right table is firstly joined using this column and then an intersection is computed.
Code Block |
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{ "function": "isvalid", "in_csv": { "wkt_column_name": "geom", "out_columns": [ "zone_id" ] } } |
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