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Smooth grid points

Source: R/cdo-smooth.R, R/cdo-smooth9.R, R/family-smooth.R
smooth.Rd

Smooth all grid points of a horizontal grid. Options is a comma-separated list of "key=value" pairs with optional parameters.

Usage

cdo_smooth(
  ifile,
  nsmooth = NULL,
  radius = NULL,
  maxpoints = NULL,
  weighted = NULL,
  weight0 = NULL,
  weightR = NULL,
  ofile = NULL
)

cdo_smooth9(
  ifile,
  nsmooth = NULL,
  radius = NULL,
  maxpoints = NULL,
  weighted = NULL,
  weight0 = NULL,
  weightR = NULL,
  ofile = NULL
)

Arguments

ifile

String with the path to the input file.

nsmooth

INTEGER - Number of times to smooth, default nsmooth=1

radius

STRING - Search radius, default radius=1deg (units: deg, rad, km, m)

maxpoints

INTEGER - Maximum number of points, default maxpoints=<gridsize>

weighted

STRING - Weighting method, default weighted=linear

weight0

FLOAT - Weight at distance 0, default weight0=0.25

weightR

FLOAT - Weight at the search radius, default weightR=0.25

ofile

String with the path to the output file.

Value

Operators that output one or more files return a character vector to the output files.

Operators that output an indefinite number of files return a string with the basename of the files.

Operatos that don't return filenames return a character vector with the string output.

Details

smooth   Smooth grid points
         Performs a N point smoothing on all input fields. The number of points used depend
         on the search radius (radius) and the maximum number of points (maxpoints).
         Per default all points within the search radius of 1degree are used.
         The weights for the points depend on the weighting method and the distance.
         The implemented weighting method is linear with constant default weights of 0.25
         at distance 0 (weight0) and at the search radius (weightR).
smooth9  9 point smoothing
         Performs a 9 point smoothing on all fields with a quadrilateral curvilinear grid.
         The result at each grid point is a weighted average of the grid point plus
         the 8 surrounding points. The center point receives a weight of 1.0, the
         points at each side and above and below receive a weight of 0.5, and corner
         points receive a weight of 0.3.
         All 9 points are multiplied by their weights and summed, then divided by
         the total weight to obtain the smoothed value. Any missing data points are
         not included in the sum; points beyond the grid boundary are considered to
         be missing. Thus the final result may be the result of an averaging with less
         than 9 points.