cmsaf.divc: Divide data by a constant.

Description Usage Arguments Value See Also Examples

View source: R/cmsaf.divc.R

Description

This function divides each element of a dataset by a given constant number.

Usage

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cmsaf.divc(
  var,
  const = 1,
  infile,
  outfile,
  nc34 = 4,
  overwrite = FALSE,
  verbose = FALSE
)

Arguments

var

Name of NetCDF variable (character).

const

Constant number (numeric).

infile

Filename of input NetCDF file. This may include the directory (character).

outfile

Filename of output NetCDF file. This may include the directory (character).

nc34

NetCDF version of output file. If nc34 = 3 the output file will be in NetCDFv3 format (numeric). Default output is NetCDFv4.

overwrite

logical; should existing output file be overwritten?

verbose

logical; if TRUE, progress messages are shown

Value

A NetCDF file including the manipulated data fields of infile is written. Standard output precision is 'double'.

See Also

Other mathematical operators: cmsaf.abs(), cmsaf.addc(), cmsaf.add(), cmsaf.div(), cmsaf.mulc(), cmsaf.mul(), cmsaf.subc(), cmsaf.sub(), divdpm(), muldpm()

Examples

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## Create an example NetCDF file with a similar structure as used by CM
## SAF. The file is created with the ncdf4 package.  Alternatively
## example data can be freely downloaded here: <https://wui.cmsaf.eu/>

library(ncdf4)

## create some (non-realistic) example data

lon <- seq(5, 15, 0.5)
lat <- seq(45, 55, 0.5)
time <- seq(as.Date("2000-01-01"), as.Date("2010-12-31"), "month")
origin <- as.Date("1983-01-01 00:00:00")
time <- as.numeric(difftime(time, origin, units = "hour"))
data <- array(250:350, dim = c(21, 21, 132))

## create example NetCDF

x <- ncdim_def(name = "lon", units = "degrees_east", vals = lon)
y <- ncdim_def(name = "lat", units = "degrees_north", vals = lat)
t <- ncdim_def(name = "time", units = "hours since 1983-01-01 00:00:00",
 vals = time, unlim = TRUE)
var1 <- ncvar_def("SIS", "W m-2", list(x, y, t), -1, prec = "short")
vars <- list(var1)
ncnew <- nc_create(file.path(tempdir(),"CMSAF_example_file.nc"), vars)
ncvar_put(ncnew, var1, data)
ncatt_put(ncnew, "lon", "standard_name", "longitude", prec = "text")
ncatt_put(ncnew, "lat", "standard_name", "latitude", prec = "text")
nc_close(ncnew)

## Divide each dataset element of the example CM SAF NetCDF file by a
## given number and write the output to a new file.
cmsaf.divc(var = "SIS", const = 100, infile = file.path(tempdir(),
 "CMSAF_example_file.nc"), outfile = file.path(tempdir(),
 "CMSAF_example_file_divc.nc"))

unlink(c(file.path(tempdir(),"CMSAF_example_file.nc"), 
 file.path(tempdir(),"CMSAF_example_file_divc.nc")))

cmsafops documentation built on Sept. 6, 2021, 9:09 a.m.