Aggregating to another, coarser domain

Change resolution/geometry of a geofield by averaging.

Usage

upscale(infield, factor=NULL, newdomain=NULL, method="mean", weights=0, ...)
upscale_factor(infield, factor, method="mean", ...)
upscale_regrid(infield, newdomain, method="mean", weights=NULL, ...)
upscale_regrid_init(olddomain, newdomain)

Arguments

infield

A geofield object.

factor

If given, the new grid is simply a coarser version of the original. factor should be a vector of 2 integers (if it is scalar, the value is repeated). It dscribes how many gridd cells in the X and Y direction are aggregated to one new grid box.

newdomain, olddomain

A geodomain or a geofield. In the second case only the domain attribute is used.

method

The aggregation method. When aggregating by a given factor, this could be a function like mean, median, max... For ergridding, only 'mean' is supported.

weights

Initialised weights for faster computation, output from upscale_regrid_init. Only used for regridding (factor=NULL).

...

Options for the method (e.g. na.rm=TRUE).

Value

A geofield object.

Details

These routines aggregate all grid boxes of the original domain into the new domain. When a factor is used, the result is exactly as expected. When regridding to a different domain, the average is taken of all original cells whose center falls inside the new grid cell. There is no compensation (yet?) for partial grid cells.

See also

zoomgrid,subgrid,regrid