R/modifyNcdfCopyVar.R

In bgctw/ncdfTools: Handling NetCDF Files

modifyNcdfCopyVar <- function(
  ### copy variable values between ncdf files
  file.con.orig        ##<< a NetCDF object pointing to the original ncdf file 
  ## FROM which to copy the variable.
  , file.con.copy = file.con.orig     ##<< a NetCDF object pointing to the 
  ## ncdf file TO which to copy the variable.
  , var.id.orig                      ##<< character string or ncdf variable id: 
  ## The name or id of the variable to copy from.
  , var.id.copy = var.id.orig        ##<< character string or ncdf variable id: 
  ## The name or id of the variable to copy to.
) {
  ##details<< Copies all values of one variable from one ncdf file to another 
  ## ncdf file and takes care of dimensions etc.
  ##details<<
  ## Two cases are implemented: 
  ## Case 1: copy of one variable and attributes from one file to another file:
  ## The dimensions of the variable to copy have to be also existent (i.e. 
  ## dimensions with the same name (not necessarily id)) in the ncdf file to 
  ## which the variable should be copied. In addition these dimensions have to 
  ## have the same sizes.
  ##
  ## Case 2: copy of one variable to another one (of different name) in the 
  ## same file.
  #
  ##seealso<<
  ##\code{\link{modifyNcdfCopyMetadata}}, \code{\link[RNetCDF]{att.copy.nc}}
  #get values to copy from
  isSameFile <- file.con.copy == file.con.orig
  if (is.character(file.con.copy)) {
    file.con.copy <- open.nc(file.con.copy, write = TRUE)
    on.exit(close.nc(file.con.copy))
  }
  if (!isSameFile) {
    if (is.character(file.con.orig)) {
      file.con.orig <- open.nc(file.con.orig)
      on.exit(close.nc(file.con.orig))
    }
  } else file.con.orig <- file.con.copy
  varInqOrig <- var.inq.nc(file.con.orig, var.id.orig)
  infoDimsOrig <- infoNcdfDims(file.con.orig)
  var.name.orig       <- varInqOrig$name
  var.type.orig       <- varInqOrig$type
  dim.names.file.orig <- infoDimsOrig$name
  dim.ids.var.orig    <- varInqOrig$dimids
  dim.lengths.orig    <- infoDimsOrig$length[dim.ids.var.orig + 1]
  ##get values to copy to
  if ((var.id.orig == var.id.copy) && (file.con.copy != file.con.orig)) {
    var.name.copy       <- var.name.orig
    dim.names.file.copy <- infoNcdfDims(file.con.copy)$name
    dim.ids.var.copy    <- match(dim.names.file.orig, dim.names.file.copy) - 1
  } else if ((var.id.orig != var.id.copy) && (file.con.copy == file.con.orig)) {
    var.name.copy    <- var.id.copy
    dim.ids.var.copy <- dim.ids.var.orig
  } else {
    stop('Either var.ids or file connections (or both) have to be different!')
  }
  ##write to file
  var.def.nc(file.con.copy, var.name.copy, var.type.orig, dim.ids.var.copy)
  modifyNcdfCopyAtts(file.con.orig, var.name.orig, var.name.copy, file.con.copy)
  ##value<< 
  ##Nothing is returned
}