com.conveyal.gtfs.storage

Class BooleanAsciiGrid

java.lang.Object

com.conveyal.gtfs.storage.BooleanAsciiGrid

public class BooleanAsciiGrid
extends Object

Loads an ESRI ASCII grid containing integers and allows looking up values as booleans (where > 0). This is used for

Constructor Summary

Constructors

Constructor and Description
BooleanAsciiGrid(InputStream inputStream, boolean gzipped)

Method Summary

Modifier and Type	Method and Description
static BooleanAsciiGrid	forEarthPopulation() Get a grid for places where population density is over 5 people per square kilometer.
boolean	getValueForCoords(double x, double y)

Methods inherited from class java.lang.Object

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

Constructor Detail

BooleanAsciiGrid

public BooleanAsciiGrid(InputStream inputStream,
                        boolean gzipped)

Method Detail

forEarthPopulation

public static BooleanAsciiGrid forEarthPopulation()

Get a grid for places where population density is over 5 people per square kilometer. We use the Gridded Population of the World v3 data set for 2015 UN-adjusted population density. This data set was downloaded at 1/4 degree resolution in ESRI ASCII grid format. The grid file was edited manually to eliminate the no-data value header, since I could not find a way to operate on no-value cells in the QGIS raster calculator. Then the raster calculator in QGIS was used with the formula ("glds00ag15@1" > 5), which makes all cells with population density above the threshold have a value of one, and all others a value of zero (since the no data value in the grid is -9999). This was then exported as another ASCII grid file, which zips well. The license for this data set is Creative Commons Attribution. See http://sedac.ciesin.columbia.edu/data/collection/gpw-v3

getValueForCoords

public boolean getValueForCoords(double x,
                                 double y)