Examples with GvrsElement org.gridfour.gvrs.GvrsElement used on opensource projects

Example 6 with GvrsElement

use of org.gridfour.gvrs.GvrsElement in project gridfour by gwlucastrig.

the class ReadGvrs method main.

public static void main(String[] args) throws IOException {
    PrintStream ps = System.out;
    long time0, time1;
    if (args.length == 0) {
        System.out.println("No input file specified");
        System.exit(0);
    }
    File file = new File(args[0]);
    System.out.println("Reading file " + file.getPath());
    boolean oneTestPerTile = args.length > 1;
    // Open the file.  The time required to open the file depends, in part,
    // on whether a supplemental index file (.gvrs) is available.  To test the
    // difference, simply delete the .gvrx file.   Deleting the index file
    // will also allow you to test whether the .gvrs file can be opened
    // successfully when an index file is not availble.
    time0 = System.nanoTime();
    GvrsFile gvrs = new GvrsFile(file, "r");
    time1 = System.nanoTime();
    double timeForOpeningFile = (time1 - time0) / 1.0e+6;
    // GvrsFile implements a method that allows an application to obtain
    // a safe copy of the specification that was used to create the
    // original GVRS file.  The specification element is the primary
    // method for obtaining descriptive metadata about the organization
    // of the file.   The example that follows demonstrates the use of
    // the specification to get some descriptive data.
    // Of course, if an application just wants to print that
    // metadata, the summarize function is the most efficient way of
    // doing so.
    GvrsFileSpecification spec = gvrs.getSpecification();
    int nRows = spec.getRowsInGrid();
    int nCols = spec.getColumnsInGrid();
    int nRowsOfTiles = spec.getRowsOfTilesInGrid();
    int nColsOfTiles = spec.getColumnsOfTilesInGrid();
    int nTiles = nRowsOfTiles * nColsOfTiles;
    ps.format("File dimensions%n");
    ps.format("  Rows:      %8d%n", nRows);
    ps.format("  Columns:   %8d%n", nCols);
    ps.format("  Tiles:     %8d%n", nTiles);
    ps.format("Time to read header and index %10.1f ms%n", timeForOpeningFile);
    gvrs.summarize(ps, true);
    // Variable length records can contain either binary or text data.
    // The VLR's are read during initial access, though their payload
    // (which may be quite large) is not read until requested by the
    // application code.
    ps.println("\n\nGVRS Metadata");
    ps.println("------------------------------------------------");
    List<GvrsMetadata> metadataList = gvrs.readMetadata();
    for (GvrsMetadata metadata : metadataList) {
        String description = metadata.getDescription();
        ps.format("  %-24.24s  %6d:  %s%n", metadata.getName(), metadata.getRecordID(), description == null ? "" : description);
    }
    gvrs.close();
    // we collect a sum of the samples.  we don't really care about
    // this value, but we collect it to ensure that Java doesn't optimize
    // away the actions inside the loop by telling it that we want a
    // computed value.
    int nTest = 4;
    double sumSample = 0;
    long nSample = 0;
    int rowStep = 1;
    int colStep = 1;
    if (oneTestPerTile) {
        rowStep = spec.getRowsInTile();
        colStep = spec.getColumnsInTile();
    }
    for (int iTest = 0; iTest < nTest; iTest++) {
        time0 = System.nanoTime();
        gvrs = new GvrsFile(file, "r");
        List<GvrsElement> elementList = gvrs.getElements();
        GvrsElement zElement = elementList.get(0);
        gvrs.setTileCacheSize(GvrsCacheSize.Large);
        for (int iRow = 0; iRow < nRows; iRow += rowStep) {
            for (int iCol = 0; iCol < nCols; iCol += colStep) {
                double sample = zElement.readValue(iRow, iCol);
                sumSample += sample;
                nSample++;
            }
        }
        time1 = System.nanoTime();
        double timeForReadingFile = (time1 - time0) / 1.0e+6;
        System.out.format("Time to read all tiles        %10.1f ms%n", timeForReadingFile);
        if (iTest == nTest - 1) {
            // on the last test, summarize
            gvrs.summarize(ps, false);
        }
        gvrs.close();
    }
    ps.println("Avg Samples " + sumSample / (double) nSample);
}

Example 7 with GvrsElement

use of org.gridfour.gvrs.GvrsElement in project gridfour by gwlucastrig.

the class PackageData method process.

void process(PrintStream ps, TestOptions options, String[] args) throws IOException {
    // The packaging of data in a Gvrs file can be thought of in terms of
    // the steps shown below.
    // 
    // 0.  Obtain descriptive parameters about source data.  In this
    // case, the application is packing data from a NetCDF source
    // and most of the descriptive parameters follow the pattern
    // established in the earlier ExtractData.java demonstration
    // 
    // 1.  Define the fixed metadata about the file (it's dimensions,
    // data type, tile organization, etc.) using a GvrsFileSpecification
    // object.
    // 
    // 2.  Open a new GvrsFile object using the settings created in step 1.
    // Adjust any run-time parameters (such as the tile-cache size)
    // according to the needs of the application.
    // 
    // 3.  Extract the data from its source and store in the Gvrs file.
    // 
    ps.format("%nGvrs Packaging Application for NetCDF-format Global DEM files%n");
    Locale locale = Locale.getDefault();
    Date date = new Date();
    SimpleDateFormat sdFormat = new SimpleDateFormat("dd MMM yyyy HH:mm z", locale);
    ps.format("Date of Execution: %s%n", sdFormat.format(date));
    String inputPath = options.getInputFile().getPath();
    File outputFile = options.getOutputFile();
    if (outputFile == null) {
        ps.format("Missing specification for output file%n");
        ps.format("Packaging application terminated%n");
        return;
    }
    ps.format("Input file:  %s%n", inputPath);
    ps.format("Output file: %s%n", outputFile.getPath());
    boolean[] matched = new boolean[args.length];
    boolean useLsop = options.scanBooleanOption(args, "-lsop", matched, false);
    // Open the NetCDF file -----------------------------------
    ps.println("Opening NetCDF input file");
    NetcdfFile ncfile = NetcdfFile.open(inputPath);
    // Identify which Variable instances carry information about the
    // geographic (latitude/longitude) coordinate system and also which
    // carry information for elevation and bathymetry.
    // the Variable that carries row-latitude information
    Variable lat;
    // the Variable that carries column-longitude information
    Variable lon;
    // the variable that carries elevation and bathymetry
    Variable z;
    lat = ncfile.findVariable("lat");
    lon = ncfile.findVariable("lon");
    z = ncfile.findVariable("elevation");
    int[] tileSize;
    // Use the input file name to format a product label
    File inputFile = new File(inputPath);
    String productLabel = inputFile.getName();
    if (productLabel.toLowerCase().endsWith(".nc")) {
        productLabel = productLabel.substring(0, productLabel.length() - 3);
    }
    if (lat == null) {
        // ETOPO1 specification
        tileSize = options.getTileSize(90, 120);
        lat = ncfile.findVariable("y");
        lon = ncfile.findVariable("x");
        z = ncfile.findVariable("z");
    } else {
        tileSize = options.getTileSize(90, 120);
    }
    if (lat == null || lon == null || z == null) {
        throw new IllegalArgumentException("Input does not contain valid lat,lon, and elevation Variables");
    }
    // using the variables from above, extract coordinate system
    // information for the product and print it to the output.
    ExtractionCoordinates extractionCoords = new ExtractionCoordinates(lat, lon);
    extractionCoords.summarizeCoordinates(ps);
    // Get the dimensions of the raster (grid) elevation/bathymetry data.
    // should be 1.
    int rank = z.getRank();
    int[] shape = z.getShape();
    int nRows = shape[0];
    int nCols = shape[1];
    ps.format("Rows:      %8d%n", nRows);
    ps.format("Columns:   %8d%n", nCols);
    int nRowsInTile = tileSize[0];
    int nColsInTile = tileSize[1];
    // Initialize the specification used to initialize the Gvrs file -------
    GvrsFileSpecification spec = new GvrsFileSpecification(nRows, nCols, nRowsInTile, nColsInTile);
    spec.setLabel(productLabel);
    // Initialize the data type.  If a zScale option was specified,
    // use integer-coded floats.  Otherwise, pick the data type
    // based on whether the NetCDF file gives integral or floating point
    // data.
    boolean isZScaleSpecified = options.isZScaleSpecified();
    float zScale = (float) options.getZScale();
    float zOffset = (float) options.getZOffset();
    // data type from NetCDF file
    DataType sourceDataType = z.getDataType();
    GvrsElementSpecification elementSpec = null;
    GvrsElementType gvrsDataType;
    if (isZScaleSpecified) {
        // the options define our data type
        int encodedLimitDepth = (int) ((LIMIT_DEPTH - zOffset) * zScale);
        int encodedLimitElev = (int) ((LIMIT_ELEVATION - zOffset) * zScale);
        elementSpec = new GvrsElementSpecificationIntCodedFloat("z", zScale, zOffset, encodedLimitDepth, encodedLimitElev, Integer.MIN_VALUE, true);
        spec.addElementSpecification(elementSpec);
        gvrsDataType = GvrsElementType.INT_CODED_FLOAT;
    } else if (sourceDataType.isIntegral()) {
        elementSpec = new GvrsElementSpecificationShort("z", LIMIT_DEPTH, LIMIT_ELEVATION, FILL_VALUE);
        spec.addElementSpecification(elementSpec);
        gvrsDataType = GvrsElementType.SHORT;
    } else {
        elementSpec = new GvrsElementSpecificationFloat("z", LIMIT_DEPTH, LIMIT_ELEVATION, Float.NaN);
        spec.addElementSpecification(elementSpec);
        gvrsDataType = GvrsElementType.FLOAT;
    }
    elementSpec.setDescription("Elevation (positive values) or depth (negative), in meters");
    elementSpec.setUnitOfMeasure("m");
    // Example with special character
    elementSpec.setLabel("die H\u00f6henlage");
    ps.println("Source date type " + sourceDataType + ", stored as " + gvrsDataType);
    ps.println("");
    // Determine whether data compression is used -------------------
    boolean compressionEnabled = options.isCompressionEnabled();
    spec.setDataCompressionEnabled(compressionEnabled);
    boolean checksumsEnalbed = options.isChecksumComputationEnabled();
    spec.setChecksumEnabled(checksumsEnalbed);
    boolean bigAddressSpaceEnabled = options.isBigAddressSpaceEnabled();
    spec.setExtendedFileSizeEnabled(bigAddressSpaceEnabled);
    double[] geoCoords = extractionCoords.getGeographicCoordinateBounds();
    spec.setGeographicCoordinates(geoCoords[0], geoCoords[1], geoCoords[2], geoCoords[3]);
    // Check to verify that the geographic coordinates and grid coordinate
    // are correctly implemented. This test is not truly part of the packaging
    // process (since it should always work), but is included here as a
    // diagnostic.
    extractionCoords.checkSpecificationTransform(ps, spec);
    // is enabled and the data type is integral.
    if (useLsop) {
        LsCodecUtility.addLsopToSpecification(spec, false);
    }
    // Create the output file and store the content from the input file.
    if (outputFile.exists()) {
        ps.println("Output file exists. Removing old file");
        boolean status = outputFile.delete();
        if (!status) {
            ps.println("Removal attempt failed");
            return;
        }
    }
    ps.println("Begin processing");
    double zMin = Double.POSITIVE_INFINITY;
    double zMax = Double.NEGATIVE_INFINITY;
    double zSum = 0;
    long nSum = 0;
    try (GvrsFile gvrs = new GvrsFile(outputFile, spec)) {
        gvrs.writeMetadata(GvrsMnc.Copyright, "This data is in the public domain and may be used free of charge");
        gvrs.writeMetadata(GvrsMnc.TermsOfUse, "This data should not be used for navigation");
        GvrsElement zElement = gvrs.getElement("z");
        gvrs.setTileCacheSize(GvrsCacheSize.Large);
        storeGeoreferencingInformation(gvrs);
        // Initialize data-statistics collection ---------------------------
        // we happen to know the range of values for the global DEM a-priori.
        // it ranges from about -11000 to 8650.  This allows us to tabulate counts
        // of which values we find in the data source.  We can use this information
        // to estimate the entropy of the source data and make a realistic
        // assessment of how many bytes would be needed to store them.
        InputDataStatCollector stats = new InputDataStatCollector(-11000, 8650, zScale);
        int[] readOrigin = new int[rank];
        int[] readShape = new int[rank];
        // -----------------------------------------------------------------
        // Package the data
        long time0 = System.currentTimeMillis();
        for (int iRow = 0; iRow < nRows; iRow++) {
            if (iRow % 1000 == 999) {
                long time1 = System.currentTimeMillis();
                double deltaT = time1 - time0;
                // rows per millis
                double rate = (iRow + 1) / deltaT;
                int nRemaining = nRows - iRow;
                long remainingT = (long) (nRemaining / rate);
                Date d = new Date(time1 + remainingT);
                ps.format("Completed %d rows, %4.1f%% of total, est completion at %s%n", iRow + 1, 100.0 * (double) iRow / (nRows - 1.0), d);
                ps.flush();
            }
            int row0 = iRow;
            int col0 = 0;
            readOrigin[0] = row0;
            readOrigin[1] = col0;
            readShape[0] = 1;
            readShape[1] = nCols;
            // happen in this application unless the input file is corrupt.
            try {
                Array array = z.read(readOrigin, readShape);
                // and store it in the Gvrs file.
                switch(gvrsDataType) {
                    case INTEGER:
                    case SHORT:
                        for (int iCol = 0; iCol < nCols; iCol++) {
                            int sample = array.getInt(iCol);
                            zElement.writeValueInt(iRow, iCol, sample);
                            stats.addSample(sample);
                            if (sample < zMin) {
                                zMin = sample;
                            }
                            if (sample > zMax) {
                                zMax = sample;
                            }
                            zSum += sample;
                            nSum++;
                        }
                        break;
                    case INT_CODED_FLOAT:
                    case FLOAT:
                    default:
                        for (int iCol = 0; iCol < nCols; iCol++) {
                            float sample = array.getFloat(iCol);
                            zElement.writeValue(iRow, iCol, sample);
                            stats.addSample(sample);
                            if (sample < zMin) {
                                zMin = sample;
                            }
                            if (sample > zMax) {
                                zMax = sample;
                            }
                            zSum += sample;
                            nSum++;
                        }
                }
            } catch (InvalidRangeException irex) {
                throw new IOException(irex.getMessage(), irex);
            }
        }
        gvrs.flush();
        long time1 = System.currentTimeMillis();
        double timeToProcess = (time1 - time0) / 1000.0;
        ps.format("Finished processing file in %4.1f seconds%n", timeToProcess);
        ps.format("Entropy for input data %4.1f bits/sample%n", stats.getEntropy());
        long outputSize = outputFile.length();
        long nCells = (long) nRows * (long) nCols;
        double bitsPerSymbol = 8.0 * (double) outputSize / (double) nCells;
        ps.format("Storage used (including overhead) %6.4f bits/sample%n", bitsPerSymbol);
        ps.format("%nSummary of file content and packaging actions------------%n");
        gvrs.summarize(ps, true);
        ps.format("Range of z values:%n");
        ps.format("  Min z: %8.3f%n", zMin);
        ps.format("  Max z: %8.3f%n", zMax);
        ps.format("  Avg z: %8.3f%n", zSum / (nSum > 0 ? nSum : 1));
    }
    // to those of the source data.
    if (options.isVerificationEnabled()) {
        int[] readOrigin = new int[rank];
        int[] readShape = new int[rank];
        ps.println("\nTesting product for data consistency with source");
        ps.println("Opening gvrs file for reading");
        long time0 = System.currentTimeMillis();
        try (GvrsFile gvrs = new GvrsFile(outputFile, "r")) {
            long time1 = System.currentTimeMillis();
            ps.println("Opening complete in " + (time1 - time0) + " ms");
            GvrsFileSpecification testSpec = gvrs.getSpecification();
            String testLabel = testSpec.getLabel();
            ps.println("Label:     " + testLabel);
            GvrsMetadata m = gvrs.readMetadata("Copyright", 0);
            if (m != null) {
                ps.println("Copyright: " + m.getString());
            }
            GvrsElement zElement = gvrs.getElement("z");
            ps.println("Element:   " + zElement.getName() + ", " + zElement.getDescription());
            gvrs.setTileCacheSize(GvrsCacheSize.Large);
            for (int iRow = 0; iRow < nRows; iRow++) {
                if (iRow % 10000 == 9999) {
                    time1 = System.currentTimeMillis();
                    double deltaT = time1 - time0;
                    // rows per millis
                    double rate = (iRow + 1) / deltaT;
                    int nRemaining = nRows - iRow;
                    long remainingT = (long) (nRemaining / rate);
                    Date d = new Date(time1 + remainingT);
                    ps.format("Completed %d rows, %4.1f%% of total, est completion at %s%n", iRow + 1, 100.0 * (double) iRow / (nRows - 1.0), d);
                    ps.flush();
                }
                int row0 = iRow;
                int col0 = 0;
                readOrigin[0] = row0;
                readOrigin[1] = col0;
                readShape[0] = 1;
                readShape[1] = nCols;
                try {
                    Array array = z.read(readOrigin, readShape);
                    switch(gvrsDataType) {
                        case INTEGER:
                            for (int iCol = 0; iCol < nCols; iCol++) {
                                int sample = array.getInt(iCol);
                                int test = zElement.readValueInt(iRow, iCol);
                                if (sample != test) {
                                    ps.println("Failure at " + iRow + ", " + iCol);
                                    test = zElement.readValueInt(iRow, iCol);
                                    System.exit(-1);
                                }
                            }
                            break;
                        case INT_CODED_FLOAT:
                            for (int iCol = 0; iCol < nCols; iCol++) {
                                double sample = array.getDouble(iCol);
                                int iSample = (int) ((sample - zOffset) * zScale + 0.5);
                                float fSample = iSample / zScale + zOffset;
                                float test = zElement.readValue(iRow, iCol);
                                double delta = Math.abs(fSample - test);
                                if (delta > 1.01 / zScale) {
                                    ps.println("Failure at " + iRow + ", " + iCol);
                                    System.exit(-1);
                                }
                            }
                            break;
                        case FLOAT:
                        default:
                            for (int iCol = 0; iCol < nCols; iCol++) {
                                float sample = array.getFloat(iCol);
                                float test = zElement.readValue(iRow, iCol);
                                if (sample != test) {
                                    ps.println("Failure at " + iRow + ", " + iCol);
                                    test = zElement.readValueInt(iRow, iCol);
                                    System.exit(-1);
                                }
                            }
                    }
                } catch (InvalidRangeException irex) {
                    throw new IOException(irex.getMessage(), irex);
                }
            }
            time1 = System.currentTimeMillis();
            ps.println("Exhaustive cross check complete in " + (time1 - time0) + " ms");
            gvrs.summarize(ps, false);
        }
    }
    ncfile.close();
}

Example 8 with GvrsElement

use of org.gridfour.gvrs.GvrsElement in project gridfour by gwlucastrig.

the class GvrsReadPerformance method testTileBlockScan.

void testTileBlockScan(PrintStream ps) throws IOException {
    try (GvrsFile gvrs = new GvrsFile(inputFile, "r")) {
        gvrs.setTileCacheSize(GvrsCacheSize.Large);
        List<GvrsElement> elementList = gvrs.getElements();
        GvrsElement element = elementList.get(0);
        GvrsElementType dType = element.getDataType();
        double avgValue = 0;
        long nSample = 0;
        long time0 = System.nanoTime();
        double sum = 0;
        if (dType == GvrsElementType.INTEGER || dType == GvrsElementType.SHORT) {
            for (int iRow = 0; iRow < nRowsOfTiles; iRow++) {
                for (int iCol = 0; iCol < nColsOfTiles; iCol++) {
                    int row0 = iRow * nRowsInTile;
                    int col0 = iCol * nColsInTile;
                    int[] block = element.readBlockInt(row0, col0, nRowsInTile, nColsInTile);
                    for (int sample : block) {
                        sum += sample;
                        nSample++;
                    }
                }
            }
        } else {
            for (int iRow = 0; iRow < nRowsOfTiles; iRow++) {
                for (int iCol = 0; iCol < nColsOfTiles; iCol++) {
                    int row0 = iRow * nRowsInTile;
                    int col0 = iCol * nColsInTile;
                    float[] block = element.readBlock(row0, col0, nRowsInTile, nColsInTile);
                    for (float sample : block) {
                        if (!Float.isNaN(sample)) {
                            sum += sample;
                            nSample++;
                        }
                    }
                }
            }
        }
        if (nSample > 0) {
            avgValue = sum / (double) nSample;
        }
        long time1 = System.nanoTime();
        double deltaT = (time1 - time0) / 1.0e+9;
        report(ps, "Block Test", deltaT, avgValue, nSample);
    }
}

Example 9 with GvrsElement

use of org.gridfour.gvrs.GvrsElement in project gridfour by gwlucastrig.

the class EntropyTabulator method process.

/**
 * Process the specified GVRS file and write a report to the specified print
 * stream.
 * <p>
 * If configured to do so, this method will write progress reports to the
 * specified print stream.
 *
 * @param ps a valid print stream, System&#46;out is a valid candidate
 * @param inputFile a reference to a GVRS file
 * @param showProgress indicates if progress reports are to be printed during
 * processing
 * @return on successful completion, a valid floating-point value; otherwise,
 * a Double&#46;NaN.
 */
public double process(PrintStream ps, File inputFile, boolean showProgress) {
    double entropy = Double.NaN;
    ps.format("%nEntropy tabulation for GVRS files%n");
    Locale locale = Locale.getDefault();
    Date date = new Date();
    SimpleDateFormat sdFormat = new SimpleDateFormat("dd MMM yyyy HH:mm z", locale);
    ps.format("Date of Execution: %s%n", sdFormat.format(date));
    String inputPath = inputFile.getPath();
    ps.format("Input file:  %s%n", inputPath);
    File parent = inputFile.getParentFile();
    File countsFile = new File(parent, TEMP_COUNT_FILE_NAME);
    // Define the specs for the entropy stats file
    GvrsFileSpecification countsSpec = new GvrsFileSpecification(65536, 65536, 256, 256);
    countsSpec.setDataCompressionEnabled(false);
    GvrsElementSpecificationInt countsElementSpec = new GvrsElementSpecificationInt("counts", 0);
    countsSpec.addElementSpecification(countsElementSpec);
    try (GvrsFile source = new GvrsFile(inputFile, "r");
        GvrsFile counts = new GvrsFile(countsFile, countsSpec)) {
        GvrsFileSpecification sourceSpec = source.getSpecification();
        int nRowsInSource = sourceSpec.getRowsInGrid();
        int nColsInSource = sourceSpec.getColumnsInGrid();
        int nRowsOfTilesInSource = sourceSpec.getRowsOfTilesInGrid();
        int nColsOfTilesInSource = sourceSpec.getColumnsOfTilesInGrid();
        int nRowsInTile = sourceSpec.getRowsInTile();
        int nColsInTile = sourceSpec.getColumnsInTile();
        GvrsElement sourceElement = source.getElements().get(0);
        GvrsElementType sourceDataType = sourceElement.getDataType();
        GvrsElement countsElement = counts.getElement("counts");
        long nSamples = 0;
        long nSymbols = 0;
        ps.println("Source File " + inputFile.getName());
        ps.format("   Rows:      %8d%n", nRowsInSource);
        ps.format("   Columns:   %8d%n", nColsInSource);
        source.setTileCacheSize(GvrsCacheSize.Small);
        counts.setTileCacheSize(2000);
        long time0 = System.currentTimeMillis();
        if (showProgress) {
            ps.format("Initializing temporary entropy tabulation file %s%n", countsFile.getPath());
            ps.flush();
        }
        // Package the data
        if (showProgress) {
            ps.format("Initialization done in %d ms%n", System.currentTimeMillis() - time0);
            ps.println("Beginning tabulation");
        }
        time0 = System.currentTimeMillis();
        for (int iTileRow = 0; iTileRow < nRowsOfTilesInSource; iTileRow++) {
            if (showProgress && iTileRow > 0) {
                long time1 = System.currentTimeMillis();
                double deltaT = time1 - time0;
                // rows per millis
                double rate = (iTileRow + 1) / deltaT;
                int nRemaining = nRowsOfTilesInSource - iTileRow;
                long remainingT = (long) (nRemaining / rate);
                Date d = new Date(time1 + remainingT);
                ps.format("Surveyed %d rows, %4.1f%% of total, est completion at %s%n", iTileRow * nRowsInTile, 100.0 * (double) iTileRow / (nRowsOfTilesInSource - 1.0), d);
                ps.flush();
            }
            int row0 = iTileRow * nRowsInTile;
            int row1 = row0 + nRowsInTile;
            if (row1 > nRowsInSource) {
                row1 = nRowsInSource;
            }
            for (int iTileCol = 0; iTileCol < nColsOfTilesInSource; iTileCol++) {
                int col0 = iTileCol * nColsInTile;
                int col1 = col0 + nColsInTile;
                if (col1 > nColsInSource) {
                    col1 = nColsInSource;
                }
                for (int iRow = row0; iRow < row1; iRow++) {
                    for (int iCol = col0; iCol < col1; iCol++) {
                        int bits;
                        if (sourceDataType == GvrsElementType.FLOAT) {
                            float sample = sourceElement.readValue(iRow, iCol);
                            bits = Float.floatToRawIntBits(sample);
                        } else {
                            bits = sourceElement.readValueInt(iRow, iCol);
                        }
                        long longIndex = ((long) bits) & 0x00ffffffffL;
                        long longRow = longIndex / 65536L;
                        long longCol = longIndex - longRow * 65536L;
                        int count = countsElement.readValueInt((int) longRow, (int) longCol);
                        countsElement.writeValueInt((int) longRow, (int) longCol, count + 1);
                        nSamples++;
                        if (count == 0) {
                            nSymbols++;
                        }
                    }
                }
            }
        }
        counts.flush();
        long time1 = System.currentTimeMillis();
        double timeToProcess = (time1 - time0) / 1000.0;
        if (showProgress) {
            ps.format("Finished surveying source file in %4.1f seconds%n", timeToProcess);
            ps.format("Performing tabulation of count data%n");
            ps.flush();
        }
        time0 = System.currentTimeMillis();
        double nSamplesDouble = (double) nSamples;
        int maxCount = 0;
        long nUnique = 0;
        long nRepeated = 0;
        KahanSummation ks = new KahanSummation();
        for (int iRow = 0; iRow < 65536; iRow++) {
            if (showProgress && (iRow & 1023) == 0 && iRow > 0) {
                time1 = System.currentTimeMillis();
                double deltaT = time1 - time0;
                // rows per millis
                double rate = (iRow + 1) / deltaT;
                int nRemaining = 65536 - iRow;
                long remainingT = (long) (nRemaining / rate);
                Date d = new Date(time1 + remainingT);
                ps.format("Tabulated %d rows, %4.1f%% of total, est completion at %s%n", iRow, 100.0 * (double) iRow / 65536.0, d);
                ps.flush();
            }
            for (int iCol = 0; iCol < 65536; iCol++) {
                int count = countsElement.readValueInt(iRow, iCol);
                if (count > 0) {
                    double p = (double) count / nSamplesDouble;
                    double s = -p * Math.log(p);
                    ks.add(s);
                    if (count > maxCount) {
                        maxCount = count;
                    }
                    if (count == 1) {
                        nUnique++;
                    } else {
                        nRepeated++;
                    }
                }
            }
        }
        // get sum of entropy calculations, and them apply
        // adjustment for base 2.
        entropy = ks.getSum() / Math.log(2.0);
        time1 = System.currentTimeMillis();
        double timeToTabulate = (time1 - time0) / 1000.0;
        ps.format("Finished processing file in %4.1f seconds%n", timeToTabulate);
        ps.format("Size of Counts File %12d%n", countsFile.length());
        ps.format("Samples:            %12d%n", nSamples);
        ps.format("Unique Symbols:     %12d%n", nUnique);
        ps.format("Repeated Symbols:   %12d%n", nRepeated);
        ps.format("Total symbols:      %12d%n", nSymbols);
        ps.format("Max count:          %12d%n", maxCount);
        ps.format("Entropy:            %9.5f%n ", entropy);
    } catch (IOException ioex) {
        ps.println("IOException accessing " + inputFile.getPath() + ", " + ioex.getMessage());
        ioex.printStackTrace(ps);
    }
    countsFile.delete();
    return entropy;
}