NCL Website header
NCL Home > Documentation > Functions > File I/O


Returns the dimension sizes of variable on a supported file.


	function filevardimsizes (
		thefile [1] : file,    
		varname [1] : string   

	return_val [*] :  integer or long



A reference to a file that was created using addfile or addfiles. Thus, it must be a supported file format.


The string name of the variable whose dimension sizes are desired.

Return value

Returns a one-dimensional array of dimension sizes for a file variable. In versions 5.x or earlier, this function always returns an integer array. In versions 6.0.0 or later, this function may return a long array. See below.


This function works just like dimsizes, but for file variables. This function should be used rather than dimsizes when the variable is in a file. The dimsizes function is very inefficient to use on file variables because it reads in the entire variable. The filevardimsizes function should be used exclusively when querying the dimensionality of variables in files.

As of version 6.0.0, this function will return type "long" if the product of the dimension sizes is greater than or equal to 2 GB.

Note: This function is exactly the same as getfilevardimsizes. It is kept under this name for historical purposes.

See Also

dimsizes, getfilevardimsizes, isfilevardim


Example 1 Consider a netCDF file where "ncdump -h" yields:

netcdf Tstorm {
        timestep = 64 ;
        lat = 33 ;
        lon = 36 ;
        timelen = 20 ;
        float t(timestep, lat, lon) ;
                t:_FillValue = -9999.f ;
        int timestep(timestep) ;
        float lat(lat) ;
        float lon(lon) ;
        char reftime(timelen) ;
                reftime:units = "text_time" ;
                reftime:long_name = "reference time" ;
  a    = addfile("$NCARG_ROOT/lib/ncarg/data/cdf/Tstorm.cdf","r")

  dimt = filevardimsizes(a,"t")  
This produces the following output:
Variable: dimt
Type: integer
Total Size: 12 bytes
            3 values
Number of Dimensions: 1
Dimensions and sizes:   [3]

(0)     64
(1)     33
(2)     36