cmsaf (version 1.9.0)

extract.period: Remove a time period.

Description

This function deletes a time period between a given start and end date from a timeseries. If start and end are the same, only this date will be removed.

Usage

extract.period(var, start, end, infile, outfile, nc34)

Arguments

var

Name of NetCDF variable (character).

start

Startdate as character in form of 'YYYY-MM-DD' (e.g., '2001-12-31').

end

Enddate as character in form of 'YYYY-MM-DD' (e.g., '2014-01-01').

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=4 the output file will be in NetCDFv4 format (numeric). Default output is NetCDFv3.

Value

A NetCDF file excluding the selected time period is written.

Examples

# NOT RUN {
## 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('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)

## Remove a 13-months period of the example CM SAF NetCDF file and write 
## the output to a new file.
   extract.period('SIS','2001-01-01','2002-01-01',
   'CMSAF_example_file.nc','CMSAF_example_file_extract.period.nc')
# }