Class GridExtent
 Object

 GridExtent

 All Implemented Interfaces:
Serializable
public class GridExtent extends Object implements Serializable
A range of grid coverage coordinates, also known as "grid envelope".GridExtent
are defined by low coordinates (often all zeros) and high coordinates, inclusive. For example a grid with a width of 512 cells can have a low coordinate of 0 and high coordinate of 511.Note: The inclusiveness of high coordinates come from ISO 19123. We follow this specification for all getters methods, but developers should keep in mind that this is the opposite of Java2D usage whereRectangle
maximal values are exclusive.GridExtent
instances are immutable and threadsafe. The same instance can be shared by differentGridGeometry
instances.Upcoming API generalization: this class may implement theGridEnvelope
interface in a future Apache SIS version. This is pending GeoAPI update. Since:
 1.0
 See Also:
 Serialized Form
Defined in the
sisfeature
module


Constructor Summary
Constructors Constructor Description GridExtent(long width, long height)
Creates a new grid extent for an image or matrix of the given size.GridExtent(DimensionNameType[] axisTypes, long[] low, long[] high, boolean isHighIncluded)
Constructs a new grid envelope set to the specified coordinates.

Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
equals(Object object)
Compares the specified object with this grid envelope for equality.GridExtent
expand(long... margins)
Expands or shrinks this grid extent by the given amount of cells along each dimension.Optional<DimensionNameType>
getAxisType(int index)
Returns the type (vertical, temporal, …) of grid axis at given dimension.int
getDimension()
Returns the number of dimensions.long
getHigh(int index)
Returns the valid maximum inclusive grid coordinate along the specified dimension.long
getLow(int index)
Returns the valid minimum inclusive grid coordinate along the specified dimension.double[]
getPointOfInterest()
Returns the grid coordinates of a representative point.long
getSize(int index)
Returns the number of integer grid coordinates along the specified dimension.double
getSize(int index, boolean minusOne)
Returns the number of grid coordinates as a double precision floating point value.int[]
getSubspaceDimensions(int s)
Returns indices of all dimensions where this grid extent has a size greater than 1.int
hashCode()
Returns a hash value for this grid envelope.GridExtent
insert(int offset, DimensionNameType axisType, long low, long high, boolean isHighIncluded)
Returns a new grid envelope with the specified dimension inserted at the given index in this grid envelope.GridExtent
reduce(int... dimensions)
Returns a grid envelope that encompass only some dimensions of this grid envelope.GridExtent
resize(long... sizes)
Sets the size of this grid extent to the given values.boolean
startsAtZero()
Returnstrue
if all low coordinates are zero.GridExtent
subsample(int... periods)
Creates a new grid extent subsampled by the given amount of cells along each grid dimensions.String
toString()
Returns a string representation of this grid envelope.



Constructor Detail

GridExtent
public GridExtent(long width, long height)
Creates a new grid extent for an image or matrix of the given size. The low grid coordinates are zeros and the axis types areDimensionNameType.COLUMN
andROW
in that order. Parameters:
width
 number of pixels in each row.height
 number of pixels in each column.

GridExtent
public GridExtent(DimensionNameType[] axisTypes, long[] low, long[] high, boolean isHighIncluded)
Constructs a new grid envelope set to the specified coordinates. The given arrays contain a minimum (inclusive) and maximum value for each dimension of the grid coverage. The lowest valid grid coordinates are often zero, but this is not mandatory. As a convenience for this common case, a nulllow
array means that all low coordinates are zero.An optional (nullable)
axisTypes
argument can be used for attaching a label to each grid axis. For example if thisGridExtent
is fourdimensional, then the axis types may be {column (x), row (y), vertical (z), {@linkplain DimensionNameType#TIME time} (t), which means that the last axis is for the temporal dimension, the third axis is for the vertical dimension, etc. This information is related to the "real world" coordinate reference system axes, but not necessarily in the same order; it is caller responsibility to ensure that the grid axes are consistent with the CRS axes. TheaxisTypes
array shall not contain duplicated elements, but may containnull
elements if the type of some axes are unknown. Parameters:
axisTypes
 the type of each grid axis, ornull
if unspecified.low
 the valid minimum grid coordinates (always inclusive), ornull
for all zeros.high
 the valid maximum grid coordinates, inclusive or exclusive depending on the next argument.isHighIncluded
true
if thehigh
values are inclusive (as in ISO 19123 specification), orfalse
if they are exclusive (as in Java2D usage). This argument does not apply tolow
values, which are always inclusive. Throws:
IllegalArgumentException
 if a coordinate value in the low part is greater than the corresponding coordinate value in the high part. See Also:
getLow()
,getHigh()
,insert(int, DimensionNameType, long, long, boolean)


Method Detail

getDimension
public final int getDimension()
Returns the number of dimensions. Returns:
 the number of dimensions.
 See Also:
reduce(int...)

startsAtZero
public boolean startsAtZero()
Returnstrue
if all low coordinates are zero. This is a very common case since many grids start their cell numbering at zero. Returns:
 whether all low coordinates are zero.

getLow
public long getLow(int index)
Returns the valid minimum inclusive grid coordinate along the specified dimension. Parameters:
index
 the dimension for which to obtain the coordinate value. Returns:
 the low coordinate value at the given dimension, inclusive.
 Throws:
IndexOutOfBoundsException
 if the given index is negative or is equals or greater than the grid dimension. See Also:
getHigh(int)

getHigh
public long getHigh(int index)
Returns the valid maximum inclusive grid coordinate along the specified dimension. Parameters:
index
 the dimension for which to obtain the coordinate value. Returns:
 the high coordinate value at the given dimension, inclusive.
 Throws:
IndexOutOfBoundsException
 if the given index is negative or is equals or greater than the grid dimension. See Also:
getLow(int)

getSize
public long getSize(int index)
Returns the number of integer grid coordinates along the specified dimension. This is equal togetHigh(dimension)  getLow(dimension) + 1
. Parameters:
index
 the dimension for which to obtain the size. Returns:
 the number of integer grid coordinates along the given dimension.
 Throws:
IndexOutOfBoundsException
 if the given index is negative or is equals or greater than the grid dimension.ArithmeticException
 if the size is too large for thelong
primitive type. See Also:
getLow(int)
,getHigh(int)

getSize
public double getSize(int index, boolean minusOne)
Returns the number of grid coordinates as a double precision floating point value. Invoking this method is equivalent to invokinggetSize(int)
and converting the result fromlong
to thedouble
primitive type, except that this method does not overflow. Parameters:
index
 the dimension for which to obtain the size.minusOne
true
for returning size−1 instead of size. Returns:
 the number of integer grid coordinates along the given dimension.

getPointOfInterest
public double[] getPointOfInterest()
Returns the grid coordinates of a representative point. This point may be used for estimating a grid resolution. The default implementation returns the median (or center) coordinates of this grid extent, but subclasses can override this method if another point is considered more representative. Returns:
 the grid coordinates of a representative point.

getSubspaceDimensions
public int[] getSubspaceDimensions(int s)
Returns indices of all dimensions where this grid extent has a size greater than 1. This method can be used for getting the grid extent of a sdimensional slice in a ndimensional cube where s ≦ n.Example: suppose that we want to get a twodimensional slice (y,z) in a fourdimensional data cube (x,y,z,t). The first step is to specify the x and t coordinates of the slice. In this example we set x to 5 and t to 8.This method returns exactly s indices. If there is more than s dimensions having a size greater than 1, then a
Above code created a slice at the requested position, but that slice still have 4 dimensions. It is a "slice" because the x and t dimensions ofGridGeometry grid = ...; // Geometry of the (x,y,z,t) grid. GridGeometry slice4D = grid.slice(new GeneralDirectPosition(5, NaN, NaN, 8));
slice4D
have only one cell. If a twodimensional slice is desired, then above operations can be completed as below. In this example, the result ofgetSubspaceDimensions(2)
call will be {1,2}.
Note that in this particular example, it would have been more efficient to executeint[] subDimensions = slice4D.getExtent().getSubspaceDimensions(2); GridGeometry slice2D = slice4D.reduce(subDimensions);
grid.reduce(1,2)
directly. ThisgetSubspaceDimensions(int)
method is more useful for inferring aslice2D
from aslice4D
which has been created elsewhere, or when we do not really want theslice2D
but only its dimension indices.SubspaceNotSpecifiedException
is thrown. If there is less than s dimensions having a size greater than 1, then the returned list of dimensions is completed with some dimensions of size 1, starting with the first dimensions in this grid extent, until there is exactly s dimensions. This this grid extent does not have s dimensions, then aCannotEvaluateException
is thrown. Parameters:
s
 number of dimensions of the subspace. Returns:
 indices of subspace dimensions, in increasing order in an array of length s.
 Throws:
SubspaceNotSpecifiedException
 if there is more than s dimensions having a size greater than 1.RuntimeException
 if this grid extent does not have at least s dimensions.

getAxisType
public Optional<DimensionNameType> getAxisType(int index)
Returns the type (vertical, temporal, …) of grid axis at given dimension. This information is provided because the grid axis type can not always be inferred from the context. Some examples are:getAxisType(0)
may returnDimensionNameType.COLUMN
,TRACK
orLINE
.getAxisType(1)
may returnDimensionNameType.ROW
,CROSS_TRACK
orSAMPLE
.getAxisType(2)
may returnDimensionNameType.VERTICAL
.getAxisType(3)
may returnDimensionNameType.TIME
.
 Parameters:
index
 the dimension for which to obtain the axis type. Returns:
 the axis type at the given dimension. May be absent if the type is unknown.
 Throws:
IndexOutOfBoundsException
 if the given index is negative or is equals or greater than the grid dimension.

insert
public GridExtent insert(int offset, DimensionNameType axisType, long low, long high, boolean isHighIncluded)
Returns a new grid envelope with the specified dimension inserted at the given index in this grid envelope. To append a new dimension after all existing dimensions, setoffset
togetDimension()
. Parameters:
offset
 where to insert the new dimension, from 0 togetDimension()
inclusive.axisType
 the type of the grid axis to add, ornull
if unspecified.low
 the valid minimum grid coordinate (always inclusive).high
 the valid maximum grid coordinate, inclusive or exclusive depending on the next argument.isHighIncluded
true
if thehigh
value is inclusive (as in ISO 19123 specification), orfalse
if it is exclusive (as in Java2D usage). This argument does not apply tolow
value, which is always inclusive. Returns:
 a new grid envelope with the specified dimension added.
 Throws:
IllegalArgumentException
 if the low coordinate value is greater than the high coordinate value.

expand
public GridExtent expand(long... margins)
Expands or shrinks this grid extent by the given amount of cells along each dimension. This method adds the given margins to the high coordinates and subtracts the same margins to the low coordinates. Parameters:
margins
 amount of cells to add or subtract. Returns:
 a grid extent expanded by the given amount, or
this
if there is no change.  Throws:
ArithmeticException
 if expanding this extent by the given margins overflowslong
capacity.

resize
public GridExtent resize(long... sizes)
Sets the size of this grid extent to the given values. This method modifies grid coordinates as if they were multiplied by (given size) / (current size), rounded toward zero and with the value farthest from zero adjusted by ±1 for having a size exactly equals to the specified value. In the common case where the low value is zero, this is equivalent to setting the high value tosize
 1.The length of the given array should be equal to
getDimension()
. If the array is shorter, missing dimensions have their size unchanged. If the array is longer, extra sizes are ignored. Parameters:
sizes
 the new grid sizes for each dimension. Returns:
 a grid extent having the given sizes, or
this
if there is no change.  Throws:
ArithmeticException
 if resizing this extent to the given size overflowslong
capacity. See Also:
GridDerivation.resize(GridExtent, double...)

reduce
public GridExtent reduce(int... dimensions)
Returns a grid envelope that encompass only some dimensions of this grid envelope. This method copies the specified dimensions of this grid envelope into a new grid envelope. The given dimensions must be in strictly ascending order without duplicated values. The number of dimensions of the sub grid envelope will bedimensions.length
.This method performs a dimensionality reduction and can be used as the converse of
insert(int, DimensionNameType, long, long, boolean)
. This method can not be used for changing dimension order. Parameters:
dimensions
 the dimensions to select, in strictly increasing order. Returns:
 the subenvelope, or
this
if the given array contains all dimensions of this grid extent.  Throws:
IndexOutOfBoundsException
 if an index is out of bounds. See Also:
getSubspaceDimensions(int)
,GridGeometry.reduce(int...)

subsample
public GridExtent subsample(int... periods)
Creates a new grid extent subsampled by the given amount of cells along each grid dimensions. This method divides low coordinates and grid sizes by the given periods, rounding toward zero. The high coordinates are adjusted accordingly (this is often equivalent to dividing high coordinates by the periods too, but a difference of one cell may exist).Note: The envelope computed from a grid extent may become larger after subsampling, not smaller. This effect can be understood intuitively if we consider that cells become larger after subsampling, which implies that accurate representation of the same envelope may require fractional cells on some grid borders.This method does not reduce the number of dimensions of the grid extent. For dimensionality reduction, seereduce(int...)
. Parameters:
periods
 the subsamplings. Length shall be equal to the number of dimension and all values shall be greater than zero. Returns:
 the subsampled extent, or
this
is subsampling results in the same extent.  Throws:
IllegalArgumentException
 if a period is not greater than zero. See Also:
GridDerivation.subsample(int...)

hashCode
public int hashCode()
Returns a hash value for this grid envelope. This value needs not to remain consistent between different implementations of the same class.

equals
public boolean equals(Object object)
Compares the specified object with this grid envelope for equality.

