CSVData.java
package org.djutils.data.csv;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.djutils.data.DataColumn;
import org.djutils.data.DataRecord;
import org.djutils.data.DataTable;
import org.djutils.data.ListDataTable;
import org.djutils.data.SimpleDataColumn;
import org.djutils.data.serialization.TextSerializationException;
import org.djutils.data.serialization.TextSerializer;
import org.djutils.exceptions.Throw;
import org.djutils.primitives.Primitive;
import de.siegmar.fastcsv.reader.NamedCsvReader;
import de.siegmar.fastcsv.reader.NamedCsvRow;
import de.siegmar.fastcsv.writer.CsvWriter;
import de.siegmar.fastcsv.writer.LineDelimiter;
/**
* CSVData takes care of reading and writing of table data in CSV format. The class can be used, e.g., as follows:
*
* <pre>
* DataTable dataTable = new ListDataTable("data", "dataTable", columns);
* Writer writer = new FileWriter("c:/data/data.csv");
* Writer metaWriter = new FileWriter("c:/data/data.meta.csv");
* CSVData.writeData(writer, metaWriter, dataTable);
* </pre>
*
* Copyright (c) 2020-2023 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
* for project information <a href="https://djutils.org" target="_blank"> https://djutils.org</a>. The DJUTILS project is
* distributed under a three-clause BSD-style license, which can be found at
* <a href="https://djutils.org/docs/license.html" target="_blank"> https://djutils.org/docs/license.html</a>. <br>
* @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
* @author <a href="https://www.tudelft.nl/pknoppers">Peter Knoppers</a>
* @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
*/
public final class CSVData
{
/**
* Utility class, no public constructor.
*/
private CSVData()
{
// utility class
}
/**
* Write the data from the data table in CSV format. The writer writes the data, whereas the metaWriter writes the metadata.
* The metadata consists of a CSV file with three columns: the id, the description, and the class. The first row after the
* header contains the id, description, and class of the data table itself. The second and further rows contain information
* about the columns of the data table.
* @param writer Writer; the writer that writes the data, e.g. to a file
* @param metaWriter Writer; the writer for the metadata
* @param dataTable DataTable; the data table to write
* @param separator char; the delimiter to use for separating entries
* @param quotechar char; the character to use for quoted elements
* @param lineDelimiter String; the line terminator to use, can be LineDelimiter.CR, LF, CRLF or PLATFORM
* @throws IOException on I/O error when writing the data
* @throws TextSerializationException on unknown data type for serialization
*/
public static void writeData(final Writer writer, final Writer metaWriter, final DataTable dataTable, final char separator,
final char quotechar, final LineDelimiter lineDelimiter) throws IOException, TextSerializationException
{
// Write the metadata file
try (CsvWriter csvMetaWriter = CsvWriter.builder().fieldSeparator(separator).quoteCharacter(quotechar)
.lineDelimiter(lineDelimiter).build(metaWriter))
{
csvMetaWriter.writeRow("id", "description", "className");
csvMetaWriter.writeRow(dataTable.getId(), dataTable.getDescription(), dataTable.getClass().getName());
for (DataColumn<?> column : dataTable.getColumns())
{
csvMetaWriter.writeRow(column.getId(), column.getDescription(), column.getValueType().getName());
}
// Assemble the serializer array
TextSerializer<?>[] serializers = new TextSerializer[dataTable.getNumberOfColumns()];
for (int i = 0; i < dataTable.getNumberOfColumns(); i++)
{
DataColumn<?> column = dataTable.getColumns().get(i);
serializers[i] = TextSerializer.resolve(column.getValueType());
}
// Write the data file
try (CsvWriter csvWriter = CsvWriter.builder().fieldSeparator(separator).quoteCharacter(quotechar)
.lineDelimiter(lineDelimiter).build(writer))
{
csvWriter.writeRow(dataTable.getColumnIds());
String[] textFields = new String[dataTable.getNumberOfColumns()];
for (DataRecord record : dataTable)
{
Object[] values = record.getValues();
for (int i = 0; i < dataTable.getNumberOfColumns(); i++)
{
textFields[i] = serializers[i].serialize(values[i]);
}
csvWriter.writeRow(textFields);
}
}
}
}
/**
* Write the data from the data table in CSV format. The writer writes the data, whereas the metaWriter writes the metadata.
* The metadata consists of a CSV file with three columns: the id, the description, and the class. The first row after the
* header contains the id, description, and class of the data table itself. The second and further rows contain information
* about the columns of the data table. The line ending used will be CRLF which is RFC 4180 compliant.
* @param writer Writer; the writer that writes the data, e.g. to a file
* @param metaWriter Writer; the writer for the metadata
* @param dataTable DataTable; the data table to write
* @throws IOException on I/O error when writing the data
* @throws TextSerializationException on unknown data type for serialization
*/
public static void writeData(final Writer writer, final Writer metaWriter, final DataTable dataTable)
throws IOException, TextSerializationException
{
writeData(writer, metaWriter, dataTable, ',', '"', LineDelimiter.CRLF);
}
/**
* Write the data from the data table in CSV format.
* @param filename String; the file name to write the data to
* @param metaFilename String; the file name to write the metadata to
* @param dataTable DataTable; the data table to write
* @throws IOException on I/O error when writing the data
* @throws TextSerializationException on unknown data type for serialization
*/
public static void writeData(final String filename, final String metaFilename, final DataTable dataTable)
throws IOException, TextSerializationException
{
FileWriter fw = null;
FileWriter mfw = null;
try
{
fw = new FileWriter(filename);
mfw = new FileWriter(metaFilename);
writeData(fw, mfw, dataTable);
}
finally
{
if (null != fw)
{
fw.close(); // May have already been closed when the CSV writer was closed, but multiple close is harmless
}
if (null != mfw)
{
mfw.close();
}
}
}
/**
* Read the data from the CSV-file into the data table. Use the metadata to reconstruct the data table.
* @param reader Reader; the reader that can read the data, e.g. from a file
* @param metaReader Reader; the writer for the metadata
* @return dataTable the data table reconstructed from the meta data and filled with the data
* @param separator char; the delimiter to use for separating entries
* @param quotechar char; the character to use for quoted elements
* @throws IOException when the CSV data was not formatted right
* @throws TextSerializationException on unknown data type for serialization
*/
public static DataTable readData(final Reader reader, final Reader metaReader, final char separator, final char quotechar)
throws IOException, TextSerializationException
{
// Read the metadata file and reconstruct the data table
List<DataColumn<?>> columns = new ArrayList<>();
try (NamedCsvReader csvMetaReader =
NamedCsvReader.builder().fieldSeparator(separator).quoteCharacter(quotechar).build(metaReader))
{
Set<String> metaHeader = csvMetaReader.getHeader();
Throw.when(
metaHeader.size() != 3 || !metaHeader.contains("id") || !metaHeader.contains("description")
|| !metaHeader.contains("className"),
IOException.class,
"header of the metafile does not contain 'id, description, className' as fields, but %s: ", metaHeader);
// table metadata
Map<String, String> tableRow = new LinkedHashMap<>();
Iterator<NamedCsvRow> it = csvMetaReader.iterator();
while (it.hasNext())
{
NamedCsvRow row = it.next();
// table metadata
if (tableRow.size() == 0)
{
tableRow.putAll(row.getFields());
if (!tableRow.get("className").endsWith("ListDataTable"))
{
throw new IOException("Currently, this method can only recreate a ListDataTable");
}
}
else
{
// column metadata
String type = row.getField("className");
Class<?> valueClass = Primitive.forName(type);
if (valueClass == null)
{
try
{
valueClass = Class.forName(type);
}
catch (ClassNotFoundException exception)
{
throw new IOException("Could not find class " + type, exception);
}
}
@SuppressWarnings({"rawtypes", "unchecked"})
DataColumn<?> column = new SimpleDataColumn(row.getField("id"), row.getField("description"), valueClass);
columns.add(column);
}
}
Throw.when(tableRow == null, IOException.class, "no table information in the metafile");
// create DataTable
ListDataTable dataTable = new ListDataTable(tableRow.get("id"), tableRow.get("description"), columns);
// Assemble the serializer array
TextSerializer<?>[] serializers = new TextSerializer[dataTable.getNumberOfColumns()];
for (int i = 0; i < dataTable.getNumberOfColumns(); i++)
{
DataColumn<?> column = dataTable.getColumns().get(i);
serializers[i] = TextSerializer.resolve(column.getValueType());
}
// Read the data file
try (NamedCsvReader csvReader =
NamedCsvReader.builder().fieldSeparator(separator).quoteCharacter(quotechar).build(reader))
{
Set<String> header = csvReader.getHeader();
Throw.when(header.size() != columns.size(), IOException.class,
"Number of columns in the data file does not match column metadata size");
for (int i = 0; i < columns.size(); i++)
{
Throw.when(!header.contains(columns.get(i).getId()), IOException.class,
"Header with id %s not found in the data file", columns.get(i).getId());
}
// Read the data file records
csvReader.forEach(row ->
{
Object[] values = new Object[columns.size()];
for (int i = 0; i < columns.size(); i++)
{
values[i] = serializers[i].deserialize(row.getField(columns.get(i).getId()));
}
dataTable.addRecord(values);
});
return dataTable;
}
}
}
/**
* Read the data from the CSV-file into the data table. Use the metadata to reconstruct the data table.
* @param reader Reader; the reader that can read the data, e.g. from a file
* @param metaReader Reader; the writer for the metadata
* @return dataTable the data table reconstructed from the meta data and filled with the data
* @throws IOException when the CSV data was not formatted right
* @throws TextSerializationException on unknown data type for serialization
*/
public static DataTable readData(final Reader reader, final Reader metaReader)
throws IOException, TextSerializationException
{
return readData(reader, metaReader, ',', '"');
}
/**
* Read the data from the CSV-file into the data table. Use the metadata to reconstruct the data table.
* @param filename String; the file name to read the data from
* @param metaFilename String; the file name to read the metadata from
* @return dataTable the data table reconstructed from the meta data and filled with the data
* @throws IOException when the CSV data was not formatted right
* @throws TextSerializationException on unknown data type for serialization
*/
public static DataTable readData(final String filename, final String metaFilename)
throws IOException, TextSerializationException
{
FileReader fr = null;
FileReader mfr = null;
try
{
fr = new FileReader(filename);
mfr = new FileReader(metaFilename);
return readData(fr, mfr);
}
finally
{
if (null != fr)
{
fr.close(); // May have already been closed when the CSV reader was closed, but multiple close is harmless
}
if (null != mfr)
{
mfr.close();
}
}
}
}