jflowmap.data.CsvFlowMapGraphReader.java Source code

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Here is the source code for jflowmap.data.CsvFlowMapGraphReader.java

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/*
 * This file is part of JFlowMap.
 *
 * Copyright 2009 Ilya Boyandin
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package jflowmap.data;

import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import jflowmap.FlowMapAttrSpec;
import jflowmap.FlowMapGraph;
import jflowmap.util.IOUtils;

import org.apache.log4j.Logger;

import at.fhj.utils.misc.FileUtils;
import au.com.bytecode.opencsv.CSVReader;

import com.google.common.base.Function;
import com.google.common.collect.Maps;

/**
 * @author Ilya Boyandin
 */
public class CsvFlowMapGraphReader {

    private static Logger logger = Logger.getLogger(CsvFlowMapGraphReader.class);

    private final FlowMapAttrSpec attrSpec;
    private final char separator;
    private final String charset;

    private FlowMapGraphBuilder builder;

    private CsvFlowMapGraphReader(FlowMapAttrSpec attrSpec, char separator, String charset) {
        this.attrSpec = attrSpec;
        this.separator = separator;
        this.charset = charset;
    }

    /**
     * Calling this method prior to readGraph() might be useful for
     * initializing FlowMapAttrSpec which can then be passed to readGraph().
     */
    public static Iterable<String> readAttrNames(String csvLocation, char separator, String charset)
            throws IOException {
        List<String> list = null;
        CSVReader csv = null;
        try {
            csv = createReader(csvLocation, separator, charset);
            String[] header = csv.readNext();
            list = new ArrayList<String>(header.length);
            for (String attr : header) {
                list.add(attr);
            }
        } catch (Exception ioe) {
            throw new IOException("Error reading from location '" + csvLocation + "': " + ioe.getMessage(), ioe);
        } finally {
            try {
                if (csv != null)
                    csv.close();
            } catch (IOException ioe) {
            }
        }
        return list;
    }

    public static FlowMapGraph readFlowMapGraph(String nodesLocation, String flowsLocation,
            FlowMapAttrSpec attrSpec, char separator, String charset) throws IOException {
        return new CsvFlowMapGraphReader(attrSpec, separator, charset).read(nodesLocation, flowsLocation);
    }

    private FlowMapGraph read(String nodesLocation, String flowsLocation) throws IOException {

        builder = new FlowMapGraphBuilder(FileUtils.getFilenameOnly(flowsLocation), attrSpec);

        parseCsv(nodesLocation, new LineParser() {
            public void apply(Map<String, String> attrs) {
                builder.addNode(attrs);
            }
        });

        parseCsv(flowsLocation, new LineParser() {
            public void apply(Map<String, String> attrs) {
                builder.addEdge(attrs);
            }
        });

        return builder.build();
    }

    private void parseCsv(String csvLocation, LineParser lp) throws IOException {
        logger.info("Parsing CSV '" + csvLocation + "'");
        CSVReader csv = null;
        int lineNum = 1;
        try {
            Map<String, Integer> colsByName = null;
            csv = createReader(csvLocation, separator, charset);
            String[] csvLine;
            while ((csvLine = csv.readNext()) != null) {
                if (lineNum == 1) {
                    // parse header
                    colsByName = createColsByNameMap(csvLine);
                } else {
                    // parse the rest of the lines
                    lp.apply(asAttrValuesMap(csvLine, colsByName));
                }
                lineNum++;
            }
        } catch (Exception ioe) {
            throw new IOException("Error loading '" + csvLocation + "' (line " + lineNum + "): " + ioe.getMessage(),
                    ioe);
        } finally {
            try {
                if (csv != null)
                    csv.close();
            } catch (IOException ioe) {
                // can't do anything about it
            }
        }
    }

    private static CSVReader createReader(String csvLocation, char separator, String charset) throws IOException {
        return new CSVReader(new InputStreamReader(IOUtils.asInputStream(csvLocation), charset), separator);
    }

    private Map<String, String> asAttrValuesMap(final String[] csvLine, Map<String, Integer> colsByName) {
        return Maps.transformValues(colsByName, new Function<Integer, String>() {
            public String apply(Integer col) {
                return csvLine[col];
            }
        });
    }

    private interface LineParser {
        void apply(Map<String, String> attrValues) throws IOException;
    }

    private Map<String, Integer> createColsByNameMap(String[] line) {
        Map<String, Integer> map = Maps.newHashMap();
        for (int i = 0; i < line.length; i++) {
            map.put(line[i], i);
        }
        return map;
    }

}