DataBackendRaster: DataBackend for Raster Objects
In mlr3spatial: Support for Spatial Objects Within the 'mlr3' Ecosystem
DataBackendRaster R Documentation
DataBackend for Raster Objects
Description
mlr3::DataBackend for terra::SpatRaster raster objects.
Read mode
There are two different ways the reading of values is performed internally:
"Block mode" reads complete rows of the raster file and subsets the requested cells.
This mode is faster than "cell mode" if the complete raster file is iterated over.
"Cell mode" reads individual cells.
This is faster than "block mode" if only a few cells are sampled.
"Block mode" is activated if $data(rows) is used with a increasing integer sequence e.g. 200:300.
If only a single cell is requested, "cell mode" is used.
Super class
mlr3::DataBackend -> DataBackendRaster
Active bindings
rownames(integer())
Returns vector of all distinct row identifiers, i.e. the contents of the primary key column.
colnames(character())
Returns vector of all column names.
nrow(integer(1))
Number of rows (observations).
ncol(integer(1))
Number of columns (variables).
stack(SpatRaster)
Raster stack.
Methods
Public methods
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Inherited methods
Method new()
Creates a new instance of this R6 class.
Usage
DataBackendRaster$new(data)
Arguments
data(terra::SpatRaster)
The input terra::SpatRaster.
Method data()
Returns a slice of the raster in the specified format.
Currently, the only supported formats is "data.table".
The rows must be addressed as vector of cells indices, columns must be
referred to via layer names. Queries for rows with no matching row id and
queries for columns with no matching column name are silently ignored.
Rows are guaranteed to be returned in the same order as rows, columns
may be returned in an arbitrary order. Duplicated row ids result in
duplicated rows, duplicated column names lead to an exception.
Usage
DataBackendRaster$data(rows, cols, data_format = "data.table")
Arguments
rowsinteger()
Row indices. Row indices start with 1 in the upper left corner in the
raster, increase from left to right and then from top to bottom. The last
cell is in the bottom right corner and the row index equals the number of
cells in the raster.
colscharacter()
Column names.
data_format(character(1))
Desired data format. Currently only "data.table" supported.
Method head()
Retrieve the first n rows.
Usage
DataBackendRaster$head(n = 6L)
Arguments
n(integer(1))
Number of rows.
Returns
data.table::data.table() of the first n rows.
Method distinct()
Returns a named list of vectors of distinct values for each column
specified. If na_rm is TRUE, missing values are removed from the
returned vectors of distinct values. Non-existing rows and columns are
silently ignored.
Usage
DataBackendRaster$distinct(rows, cols, na_rm = TRUE)
Arguments
rowsinteger()
Row indices. Row indices start with 1 in the upper left corner in the
raster, increase from left to right and then from top to bottom. The last
cell is in the bottom right corner and the row index equals the number of
cells in the raster.
colscharacter()
Column names.
na_rmlogical(1)
Whether to remove NAs or not.
Returns
Named list() of distinct values.
Method missings()
Returns the number of missing values per column in the specified slice
of data. Non-existing rows and columns are silently ignored.
Usage
DataBackendRaster$missings(rows, cols)
Arguments
rowsinteger()
Row indices. Row indices start with 1 in the upper left corner in the
raster, increase from left to right and then from top to bottom. The last
cell is in the bottom right corner and the row index equals the number of
cells in the raster.
colscharacter()
Column names.
Returns
Total of missing values per column (named numeric()).
Method coordinates()
Returns the coordinates of rows.
If rows is missing, all coordinates are returned.
Usage
DataBackendRaster$coordinates(rows)
Arguments
rowsinteger()
Row indices. Row indices start with 1 in the upper left corner in the
raster, increase from left to right and then from top to bottom. The last
cell is in the bottom right corner and the row index equals the number of
cells in the raster.
Returns
data.table::data.table() of coordinates of rows.
mlr3spatial documentation built on Aug. 12, 2025, 1:08 a.m.
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| DataBackendRaster | R Documentation |
DataBackend for Raster Objects
Description
mlr3::DataBackend for terra::SpatRaster raster objects.
Read mode
There are two different ways the reading of values is performed internally:
"Block mode" reads complete rows of the raster file and subsets the requested cells. This mode is faster than "cell mode" if the complete raster file is iterated over.
"Cell mode" reads individual cells. This is faster than "block mode" if only a few cells are sampled.
"Block mode" is activated if $data(rows) is used with a increasing integer sequence e.g. 200:300.
If only a single cell is requested, "cell mode" is used.
Super class
mlr3::DataBackend -> DataBackendRaster
Active bindings
rownames(
integer())
Returns vector of all distinct row identifiers, i.e. the contents of the primary key column.colnames(
character())
Returns vector of all column names.nrow(
integer(1))
Number of rows (observations).ncol(
integer(1))
Number of columns (variables).stack(
SpatRaster)
Raster stack.
Methods
Public methods
Inherited methods
Method new()
Creates a new instance of this R6 class.
Usage
DataBackendRaster$new(data)
Arguments
data(terra::SpatRaster)
The input terra::SpatRaster.
Method data()
Returns a slice of the raster in the specified format.
Currently, the only supported formats is "data.table".
The rows must be addressed as vector of cells indices, columns must be referred to via layer names. Queries for rows with no matching row id and queries for columns with no matching column name are silently ignored.
Rows are guaranteed to be returned in the same order as rows, columns
may be returned in an arbitrary order. Duplicated row ids result in
duplicated rows, duplicated column names lead to an exception.
Usage
DataBackendRaster$data(rows, cols, data_format = "data.table")
Arguments
rowsinteger()
Row indices. Row indices start with 1 in the upper left corner in the raster, increase from left to right and then from top to bottom. The last cell is in the bottom right corner and the row index equals the number of cells in the raster.colscharacter()
Column names.data_format(
character(1))
Desired data format. Currently only"data.table"supported.
Method head()
Retrieve the first n rows.
Usage
DataBackendRaster$head(n = 6L)
Arguments
n(
integer(1))
Number of rows.
Returns
data.table::data.table() of the first n rows.
Method distinct()
Returns a named list of vectors of distinct values for each column
specified. If na_rm is TRUE, missing values are removed from the
returned vectors of distinct values. Non-existing rows and columns are
silently ignored.
Usage
DataBackendRaster$distinct(rows, cols, na_rm = TRUE)
Arguments
rowsinteger()
Row indices. Row indices start with 1 in the upper left corner in the raster, increase from left to right and then from top to bottom. The last cell is in the bottom right corner and the row index equals the number of cells in the raster.colscharacter()
Column names.na_rmlogical(1)
Whether to remove NAs or not.
Returns
Named list() of distinct values.
Method missings()
Returns the number of missing values per column in the specified slice of data. Non-existing rows and columns are silently ignored.
Usage
DataBackendRaster$missings(rows, cols)
Arguments
rowsinteger()
Row indices. Row indices start with 1 in the upper left corner in the raster, increase from left to right and then from top to bottom. The last cell is in the bottom right corner and the row index equals the number of cells in the raster.colscharacter()
Column names.
Returns
Total of missing values per column (named numeric()).
Method coordinates()
Returns the coordinates of rows.
If rows is missing, all coordinates are returned.
Usage
DataBackendRaster$coordinates(rows)
Arguments
rowsinteger()
Row indices. Row indices start with 1 in the upper left corner in the raster, increase from left to right and then from top to bottom. The last cell is in the bottom right corner and the row index equals the number of cells in the raster.
Returns
data.table::data.table() of coordinates of rows.
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