Function used to read matrices from a file (in csv form) - Java java.lang

Java examples for java.lang:Math Matrix

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Description

Function used to read matrices from a file (in csv form)

Demo Code

/**/*from  w w  w .  j  ava 2 s  . c  o m*/
 * MatrixHelper.java
 * 
 * Revision History:<br>
 * Jan 14, 2009 bpaulson - File created
 * 
 * <p>
 * 
 * <pre>
 * This work is released under the BSD License:
 * (C) 2008 Sketch Recognition Lab, Texas A&amp;M University (hereafter SRL @ TAMU)
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Sketch Recognition Lab, Texas A&amp;M University 
 *       nor the names of its contributors may be used to endorse or promote 
 *       products derived from this software without specific prior written 
 *       permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY SRL @ TAMU ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL SRL @ TAMU BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * </pre>
 */
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import Jama.Matrix;

public class Main{
    /**
     * Function used to read matrices from a file (in csv form)
     * 
     * @param file
     *            path of file to read from
     * @return list of matrices read
     * @throws IOException
     */
    public static List<Matrix> readMatricesFromFile(String file)
            throws IOException {
        List<Matrix> matList = new ArrayList<Matrix>();
        BufferedReader rdr = new BufferedReader(new FileReader(file));
        List<List<Double>> mat = new ArrayList<List<Double>>();
        String line;
        while ((line = rdr.readLine()) != null) {

            // new matrix
            if (line.startsWith("]")) {
                if (mat.size() > 0) {
                    matList.add(toMatrix(mat));
                }
                mat.clear();
            } else if (!line.startsWith("[")) {

                // parse line
                List<Double> lineVals = new ArrayList<Double>();
                while (line.contains(",")) {
                    String num = line.trim()
                            .substring(0, line.indexOf(','));
                    lineVals.add(Double.parseDouble(num));
                    line = line.substring(line.indexOf(',') + 1);
                }

                // parse last value
                if (line.compareToIgnoreCase("") != 0)
                    lineVals.add(Double.parseDouble(line));

                mat.add(lineVals);
            }
        }

        // add last matrix
        if (mat.size() > 0) {
            matList.add(toMatrix(mat));
        }

        return matList;
    }
    /**
     * Convert a list of a list of doubles into an actual matrix object
     * 
     * @param matrix
     *            list of a list of doubles to convert
     * @return matrix object
     */
    public static Matrix toMatrix(List<List<Double>> matrix) {
        if (matrix.size() < 1)
            return new Matrix(0, 0);
        if (matrix.get(0).size() < 1)
            return new Matrix(1, 0);
        int numRows = matrix.size();
        int numCols = matrix.get(0).size();
        for (int i = 0; i < matrix.size(); i++) {
            if (matrix.get(i).size() > numCols)
                numCols = matrix.get(i).size();
        }
        Matrix m = new Matrix(numRows, numCols);
        for (int i = 0; i < matrix.size(); i++) {
            for (int j = 0; j < matrix.get(i).size(); j++) {
                m.set(i, j, matrix.get(i).get(j));
            }
        }
        return m;
    }
}

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