eu.slipo.athenarc.triplegeo.tools

Class RdfToCsv

java.lang.Object

eu.slipo.athenarc.triplegeo.tools.RdfToCsv

All Implemented Interfaces:

ReverseConverter

public class RdfToCsv
extends java.lang.Object
implements ReverseConverter

Main entry point of the utility for reconverting triples from a RDF graph into a CSV file. LIMITATIONS: There are certain limitations in representing geometries and complex attribute values in CSV format: - In case that there are mixed geometry types in input geometries (e.g., some are points while others are polygons), these are retained in the CSV file. - Apart from a delimiter, configuration files for CSV records may also specify whether there is a quote character in string values - Reverse transformation discards attribute values that contain the quote or delimiter characters; otherwise, the CSV file may be malformed.

Version:

2.0

Author:

Kostas Patroumpas

Field Summary

Fields

Modifier and Type	Field and Description
(package private) java.lang.String	attrGeom
private static org.opengis.referencing.crs.CRSAuthorityFactory	crsFactory
private ReverseConfiguration	currentConfig
(package private) java.lang.String	delimiter
private java.lang.String	encoding
(package private) Assistant	myAssistant
(package private) java.lang.Integer	numRecs
private java.lang.String	outputFile
(package private) java.lang.String	quotes
private com.vividsolutions.jts.io.WKTReader	reader
private org.opengis.referencing.operation.MathTransform	reproject
(package private) int	sourceSRID
(package private) int	targetSRID
private java.io.BufferedWriter	writer

Constructor Summary

Constructors

Constructor and Description
RdfToCsv(ReverseConfiguration config, java.lang.String outFile, int sourceSRID, int targetSRID) Constructor for the reverse transformation process from RDF to CSV file.

Method Summary

Modifier and Type	Method and Description
void	close() Closes output file, once all results have been written.
boolean	createSchema(java.util.List<java.lang.String> attrList, org.apache.jena.query.QuerySolution sol) Determine schema with all attribute names to be used as the header of CSV file.
com.vividsolutions.jts.geom.Geometry	getGeometry(java.lang.String g) Identifies SRID (EPSG code) and geometry type from a WKT literal.
java.lang.String	getGeometrySpec(org.apache.jena.rdf.model.Literal g) Identifies SRID (EPSG code) and geometry type from a WKT literal.
java.lang.String	getGeometrySpec(java.lang.String g) Cleans up geometry literals and generates extended WKT (EWKT) representation, which includes the SRID (EPSG code).
java.lang.Integer	store(java.util.List<java.lang.String> attrList, java.util.List<java.util.List<java.lang.String>> results) Creates a feature collection from current batch of records and writes them into the output CSV file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

myAssistant

Assistant myAssistant

reproject

private org.opengis.referencing.operation.MathTransform reproject

reader

private com.vividsolutions.jts.io.WKTReader reader

sourceSRID

int sourceSRID

targetSRID

int targetSRID

currentConfig

private ReverseConfiguration currentConfig

outputFile

private java.lang.String outputFile

encoding

private java.lang.String encoding

writer

private java.io.BufferedWriter writer

delimiter

java.lang.String delimiter

quotes

java.lang.String quotes

attrGeom

java.lang.String attrGeom

numRecs

java.lang.Integer numRecs

crsFactory

private static final org.opengis.referencing.crs.CRSAuthorityFactory crsFactory

Constructor Detail

RdfToCsv

public RdfToCsv(ReverseConfiguration config,
                java.lang.String outFile,
                int sourceSRID,
                int targetSRID)

Constructor for the reverse transformation process from RDF to CSV file.

Parameters:

config - Parameters for Reverse Transformation.

outFile - Path to the output CSV file.

sourceSRID - Spatial reference system (EPSG code) of geometries in the input RDF triples

targetSRID - Spatial reference system (EPSG code) of the output CSV file

Method Detail

close

public void close()

Closes output file, once all results have been written.

Specified by:

close in interface ReverseConverter

createSchema

public boolean createSchema(java.util.List<java.lang.String> attrList,
                            org.apache.jena.query.QuerySolution sol)

Determine schema with all attribute names to be used as the header of CSV file. In case of CSV files, there is no need to specify data types for attributes.

Specified by:

createSchema in interface ReverseConverter

Parameters:

attrList - List of attribute names. Attributes in the schema will be created in the same order as specified in the SELECT query that fetches results from the RDF graph.

sol - A single result (record) from a SELECT query in SPARQL.

Returns:

True if attribute schema has been created successfully; otherwise, False.

getGeometrySpec

public java.lang.String getGeometrySpec(java.lang.String g)

Cleans up geometry literals and generates extended WKT (EWKT) representation, which includes the SRID (EPSG code).

Specified by:

getGeometrySpec in interface ReverseConverter

Parameters:

g - A geometry WKT string.

Returns:

An extended WKT (EWKT) representation of the geometry, which includes its SRID.

store

public java.lang.Integer store(java.util.List<java.lang.String> attrList,
                               java.util.List<java.util.List<java.lang.String>> results)

Creates a feature collection from current batch of records and writes them into the output CSV file.

Specified by:

store in interface ReverseConverter

Parameters:

attrList - List of attribute names.

results - Collection of records in the current batch.

Returns:

The number of records resulted in the current batch.

getGeometrySpec

public java.lang.String getGeometrySpec(org.apache.jena.rdf.model.Literal g)

Description copied from interface: ReverseConverter

Identifies SRID (EPSG code) and geometry type from a WKT literal. Applicable in reverse transformation into shapefile format.

Specified by:

getGeometrySpec in interface ReverseConverter

Parameters:

g - A geometry WKT literal.

Returns:

A string that concatenates the geometry type and the SRID of the given WKT literal.

getGeometry

public com.vividsolutions.jts.geom.Geometry getGeometry(java.lang.String g)

Description copied from interface: ReverseConverter

Identifies SRID (EPSG code) and geometry type from a WKT literal. Applicable in reverse transformation into GeoJson format.

Specified by:

getGeometry in interface ReverseConverter

Parameters:

g - A geometry WKT literal.

Returns: