Getting variable names from netCDF file

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Hi I am wondering how to get the names of all variables in a netCDF file. In ncdf4 this is easy with:

nc <- nc_open("someFile.nc") names(nc$var)

Is there an equivalent method in RNetCDF?

[mjwoods]

Hi @bfordAIMS , RNetCDF mainly aims to provide a low-level interface to the NetCDF C library, so it lacks some of the convenience of ncdf4. But it has some advantages too, by exposing more functionality of the C library and allowing access to more advanced data types.

The simplest equivalent to names(nc$var) in RNetCDF is:

names(read.nc(nc, recursive=FALSE))

Please note that this command also reads the contents of variables, which you may want to avoid for large files.

To read only the variable names in RNetCDF, you could do this:

sapply(seq_len(file.inq.nc$nvars), function(x) {var.inq.nc(nc, x-1)$name})

It involves first finding the number of variables using file.inq.nc, then looping through the variables by numeric identifier to find their names with var.inq.nc.

If your file uses groups, the above command will only show variables in the root group. To see all the variables, you could write a recursive function using the code for read.nc as a guide: https://github.com/mjwoods/RNetCDF/blob/master/R/RNetCDF.R

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Thank you @mjwoods! This is great.

[mjwoods]

Thanks @bfordAIMS , I will close the issue, but please feel free to ask further questions here if needed.