R/infoNcdfAtts.R

In ncdf.tools: Easier 'NetCDF' File Handling

infoNcdfAtts <- function(
  ##title<< Print a summary of all netCDF variable attributes
   file.con   ##<< a NetCDF object pointing to the respective netCDF file.
   , var.id ='NC_GLOBAL'  ##<< the name or id of the variable for which to display attributes.
)
  ##description<< This function returns a summary of all attributes of a single variable
  ## in a netCDF file. 
  ##details<<
  ## If an id or variable name is given for 'var.id ', attributes from one variable are returned.
  ## Global attributes are returned if 'NC_GLOBAL' is given. 
  ##seealso<<
  ##\code{\link{infoNcdfDims}}, \code{\link{infoNcdfVars}}, \code{\link[RNetCDF]{att.inq.nc}}
{
  close.file =  FALSE
  if (inherits(file.con, 'character')) {
    if (file.exists(file.con)) {
      file.con =  open.nc(file.con)
      close.file =  TRUE
    } else {
      stop(paste('File',  file.con, 'not existent!'))
    }
  }
  if  (var.id == 'NC_GLOBAL') {
    n.atts              <- file.inq.nc(file.con)$ngatts
  } else {
    n.atts               <- var.inq.nc(file.con,var.id)$natts
  }
  ##value<<
  ## A matrix containing the name, value and type (columns) of all attributes (rows)
  att.info <- matrix(NA, n.atts, 3)
  if (n.atts > 0) {
    colnames(att.info)   <- c('name', 'value', 'type')
    for (i in 1:n.atts) {
      att.info[i,1]    <- att.inq.nc(file.con, var.id, i - 1)$name
      att.values.t     <- att.get.nc(file.con, var.id,i - 1)
      if (length(att.values.t) > 1)
        att.values.t <- paste(att.values.t,collapse='; ')
      att.info[i,2]    <- att.values.t
      att.info[i,3]    <- att.inq.nc(file.con,var.id,i-1)$type
    }
  }
  if (close.file)
    close.nc(file.con)
  return(att.info)
}