Helper functions for GDAL raster data types

These are convenience functions that return information about a raster data type, return the smallest data type that can fully express two input data types, or find the smallest data type able to support specified requirements.

Usage

dt_size(dt, as_bytes = TRUE)

dt_is_complex(dt)

dt_is_integer(dt)

dt_is_floating(dt)

dt_is_signed(dt)

dt_union(dt, dt_other)

dt_union_with_value(dt, value, is_complex = FALSE)

dt_find(bits, is_signed, is_floating, is_complex = FALSE)

dt_find_for_value(value, is_complex = FALSE)

Arguments

dt

Character string containing a GDAL data type name (e.g., "Byte", "Int16", "UInt16", "Int32", "UInt32", "Float32", "Float64", etc.)

as_bytes

Logical value, TRUE to return data type size in bytes (the default), FALSE to return the size in bits.

dt_other

Character string containing a GDAL data type name.

value

Numeric value for which to find a data type (passing the real part if is_complex = TRUE).

is_complex

Logical value, TRUE if value is complex (default is FALSE), or if complex values are necessary in dt_find().

bits

Integer value specifying the number of bits necessary.

is_signed

Logical value, TRUE if negative values are necessary.

is_floating

Logical value, TRUE if non-integer values are necessary.

Details

dt_size() returns the data type size in bytes by default, optionally in bits (returns zero if dt is not recognized).

dt_is_complex() returns TRUE if the passed type is complex (one of CInt16, CInt32, CFloat32 or CFloat64), i.e., if it consists of a real and imaginary component.

dt_is_integer() returns TRUE if the passed type is integer (one of Byte, Int16, UInt16, Int32, UInt32, CInt16, CInt32).

dt_is_floating() returns TRUE if the passed type is floating (one of Float32, Float16, Float64, CFloat16, CFloat32, CFloat64).

dt_is_signed() returns TRUE if the passed type is signed.

dt_union() returns the smallest data type that can fully express both input data types (returns a data type name as character string).

dt_union_with_value() unions a data type with the data type found for a given value, and returns the resulting data type name as character string.

dt_find() finds the smallest data type able to support the given requirements (returns a data type name as character string).

dt_find_for_value() finds the smallest data type able to support the given value (returns a data type name as character string).

See also

GDALRaster$getDataTypeName()

Examples

elev_file <- system.file("extdata/storml_elev.tif", package="gdalraster")
ds <- new(GDALRaster, elev_file)

ds$getDataTypeName(band = 1) |> dt_size()
#> [1] 2
ds$getDataTypeName(band = 1) |> dt_size(as_bytes = FALSE)
#> [1] 16
ds$getDataTypeName(band = 1) |> dt_is_complex()
#> [1] FALSE
ds$getDataTypeName(band = 1) |> dt_is_integer()
#> [1] TRUE
ds$getDataTypeName(band = 1) |> dt_is_floating()
#> [1] FALSE
ds$getDataTypeName(band = 1) |> dt_is_signed()
#> [1] TRUE

ds$close()

f <- system.file("extdata/complex.tif", package="gdalraster")
ds <- new(GDALRaster, f)

ds$getDataTypeName(band = 1) |> dt_size()
#> [1] 8
ds$getDataTypeName(band = 1) |> dt_size(as_bytes = FALSE)
#> [1] 64
ds$getDataTypeName(band = 1) |> dt_is_complex()
#> [1] TRUE
ds$getDataTypeName(band = 1) |> dt_is_integer()
#> [1] FALSE
ds$getDataTypeName(band = 1) |> dt_is_floating()
#> [1] TRUE
ds$getDataTypeName(band = 1) |> dt_is_signed()
#> [1] TRUE

ds$close()

dt_union("Byte", "Int16")
#> [1] "Int16"
dt_union_with_value("Byte", -1)
#> [1] "Int16"
dt_union_with_value("Byte", 256)
#> [1] "UInt16"

dt_find(bits = 32, is_signed = FALSE, is_floating = FALSE)
#> [1] "UInt32"
dt_find_for_value(0)
#> [1] "Byte"
dt_find_for_value(-1)
#> [1] "Int8"
dt_find_for_value(NaN)
#> [1] "Float64"
dt_find_for_value(.Machine$integer.max)
#> [1] "UInt32"