com.conveyal.r5.analyst.cluster

Class AccessGridWriter

java.lang.Object

com.conveyal.r5.analyst.cluster.AccessGridWriter

public class AccessGridWriter
extends Object

Random-access access grid writer - write arrays into offsets in an access grid format file (3-d array) * Access grids look like this: Header (ASCII text "ACCESSGR") (note that this header is eight bytes, so the full grid can be mapped into a Javascript typed array if desired) Version, 4-byte integer (4 byte int) Web mercator zoom level (4 byte int) west (x) edge of the grid, i.e. how many pixels this grid is east of the left edge of the world (4 byte int) north (y) edge of the grid, i.e. how many pixels this grid is south of the top edge of the world (4 byte int) width of the grid in pixels (4 byte int) height of the grid in pixels (4 byte int) number of values per pixel (repeated 4-byte int) values of each pixel in row major order. Values within a given pixel are delta coded.

Field Summary

Fields

Modifier and Type	Field and Description
static long	HEADER_SIZE The offset to get to the data section of the access grid file
static org.slf4j.Logger	LOG
static int	ORIGIN_VERSION The version of the origins we consume
static int	VERSION The version of the access grids we produce

Constructor Summary

Constructors

Constructor and Description
AccessGridWriter(int zoom, int west, int north, int width, int height, int nValuesPerPixel) Create a new in-memory access grid writer for a width x height x nValuesPerPixel array.

Method Summary

Modifier and Type	Method and Description
byte[]	getBytes()
void	writePixel(int x, int y, int[] pixelValues)

Methods inherited from class java.lang.Object

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

Field Detail

LOG

public static final org.slf4j.Logger LOG

VERSION

public static final int VERSION

The version of the access grids we produce

See Also:

Constant Field Values

ORIGIN_VERSION

public static final int ORIGIN_VERSION

The version of the origins we consume

See Also:

Constant Field Values

HEADER_SIZE

public static final long HEADER_SIZE

The offset to get to the data section of the access grid file

See Also:

Constant Field Values

Constructor Detail

AccessGridWriter

public AccessGridWriter(int zoom,
                        int west,
                        int north,
                        int width,
                        int height,
                        int nValuesPerPixel)
                 throws IOException

Create a new in-memory access grid writer for a width x height x nValuesPerPixel array.

Throws:

IOException

Method Detail

writePixel

public void writePixel(int x,
                       int y,
                       int[] pixelValues)
                throws IOException

Throws:

IOException

getBytes

public byte[] getBytes()