udConvertGrid: Unit conversion

In SantanderMetGroup/convertR: A climate4R Package for Unit Conversion and Variable Derivation

Unit conversion

Description

Unit conversion for climate4R objects

Usage

udConvertGrid(grid, new.units)

Arguments

grid	Input grid (either regular, rotated or station data).
new.units	Character string vector indicating a udunits-parseable unit definition. See Details.

Details

Unit conversion and consistency checks

This function is a wrapper of the ud.convert function from the UCAR's UDUNITS R bindings, tailored to the climate4R CDM. The function performs a number of checks in order to ensure that: (i) the units of the input grid and the new units are recognised by the UDUNITS database and (ii), that the conversion between input and output units is possible. This is internally achieved by the functions (i) ud.is.parseable and (ii) ud.are.convertible from package udunits2.

Multigrid support

The function supports multigrids as input. Note that in this case, the length of the new.units vector should match the number of variables within the multigrid (shape of 'var' dimension), and preserve its ordering (otherwise failing in the above-mentioned consistency checks).

Value

Returns (invisibly) a grid similar to the input, but with new units

Author(s)

J Bedia

References

https://www.unidata.ucar.edu/software/udunits

See Also

getGridUnits, for accessing the "units" attribute of a grid and setGridUnits, to manually modify it.

Examples

library(transformeR)
require(climate4R.datasets)
data("NCEP_Iberia_ta850")
# Converting from Kelvin to Celsius:
getGridUnits(NCEP_Iberia_ta850)
range(NCEP_Iberia_ta850$Data, na.rm = TRUE)
ta850_degC <- udConvertGrid(grid = NCEP_Iberia_ta850, new.units = "celsius")
getGridUnits(ta850_degC)
range(ta850_degC$Data, na.rm = TRUE)
# Converting from Pascals to mmHg:
data("NCEP_Iberia_psl")
getGridUnits(NCEP_Iberia_psl)
range(NCEP_Iberia_psl$Data, na.rm = TRUE)
psl_mmHg <- udConvertGrid(NCEP_Iberia_psl, new.units = "mmHg")
getGridUnits(psl_mmHg)
range(psl_mmHg$Data, na.rm = TRUE)
# Dealing with multigrids:
mg <- makeMultiGrid(NCEP_Iberia_psl, NCEP_Iberia_ta850)
getVarNames(mg)
getGridUnits(mg)
# Convert all variables:
mg.conv <- udConvertGrid(mg, new.units = c("mmHg", "celsius"))
getGridUnits(mg.conv)

SantanderMetGroup/convertR documentation built on June 30, 2023, 3:03 a.m.