R: Rename an Existing Variable in a netCDF File

ncvar_rename {ncdf4} | R Documentation

## Rename an Existing Variable in a netCDF File

### Description

Renames an existing variable that currently is part of a netCDF file that is on disk.

### Usage

     ncvar_rename( nc, old_varname, new_varname, verbose=FALSE )

### Arguments

`nc` | The already-existing netCDF file that we want to manipulate. This must be a value of class "ncdf4" returned by a call to `nc_open``(...,write=TRUE).`
`old_varname` | The variable in the file that is to be renamed. This can be a string with the name of the variable to be renamed, or a value of class "ncvar4" returned by a call to `ncvar_def()`.
`new_varname` | A string containing the new name of the variable.
`verbose` | If true, run verbosely.

### Details

This call allows you to rename a variable that already exists in a netCDF file.

NOTE that the return value of this routine should replace the old netCDF file handle that you were using. This newly returned value reflects the modifications to the file that were accomplished by calling this routine.

### Value

The updated value of nc that contains the new name. This needs to replace the old value of nc in the code. I..e, `ncid <- ncvar_rename( ncid, ... )`.

### Author(s)

David W. Pierce dpierce@ucsd.edu

### References

http://dwpierce.com/software

### See Also

`ncdim_def`, `nc_create`, `ncvar_def`.

### Examples

    #===================================================================
    # PART 1.  MAKE A TEST NETCDF FILE THAT WE WILL MANIPULATE IN PART 2
    #===================================================================

    #----------------
    # Make dimensions
    #----------------
    xvals <- 1:360
    yvals <- -90:90

    nx <- length(xvals)
    ny <- length(yvals)

    xdim <- ncdim_def( 'Lon', 'degreesE', xvals )
    ydim <- ncdim_def( 'Lat', 'degreesE', yvals )
    tdim <- ncdim_def( 'Time', 'days since 1900-01-01', 0, unlim=TRUE )

    #---------
    # Make var
    #---------
    mv <- 1.e30     # missing value
    var_temp <- ncvar_def( 'Temperature', 'K', list(xdim,ydim,tdim), mv )

    #---------------------
    # Make new output file
    #---------------------
    output_fname <- 'test_real3d.nc'
    ncid_new <- nc_create( output_fname, list(var_temp))

    #-------------------------------
    # Put some test data in the file
    #-------------------------------
    data_temp <- array(0.,dim=c(nx,ny,1))
    for( j in 1:ny )
    for( i in 1:nx )
            data_temp[i,j,1] <- sin(i/10)*sin(j/10)

    ncvar_put( ncid_new, var_temp, data_temp, start=c(1,1,1), count=c(nx,ny,1))

    #--------------------------
    # Close our new output file
    #--------------------------
    nc_close( ncid_new )

    #===========================================================================
    # PART 2.  RENAME A NEW VARIABLE TO THE FILE
    #===========================================================================

    #-------------------------------------------------
    # Open the existing file we're going to manipulate
    #-------------------------------------------------
    ncid_old <- nc_open( output_fname, write=TRUE )

    old_varname <- 'Temperature'
    new_varname <- 'T'

    ncid_old <- ncvar_rename( ncid_old, old_varname, new_varname )

    print(ncid_old)

    nc_close( ncid_old )

    # Clean up our example
    file.remove( output_fname )

[Package ncdf4 version 1.17 Index]