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addfiles_GetVar

Creates a reference that spans multiple data files and returns metadata.

Prototype

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"

	function addfiles_GetVar (
		f         : list,    
		files [*] : string,  
		name      : string   
	)

	return_val [1] :  list

Arguments

f

The list of files returned from addfiles returns (e.g. f_list = addfiles (fils+".nc", "r")).

files

A one-dimensional array that equal the file names to access.

name

A one-dimensional array or scalar value equal to the variable to be retrieved from f. Must match the syntax and case sensitivity of the variable.

Return value

An array of any dimensionality or type. This is the variable selected by name on files.

Description

A follow-on to addfiles (which by default does not return any metadata) that reads in a variable AND returns the appropriate attributes and coordinate variables. Assumes that in the case of an addfiles join argument, that the leftmost dimension is the coordinate variable that must be specially treated.

See Also

addfiles

Examples

Example 1: Consider a directory that has multiple netCDF files: annual_11.nc, annual_2.nc,..., annual_5.nc. Each file has variables with 12 time steps.

     load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl" 
                                     
     fils = systemfunc("ls /model/annual*nc")
     f    = addfiles(fils, "r")           ; note the "s" of addfile
     T    = addfiles_GetVar(f,fils,"T")
     printVarSummary(T)

The output yields:

     Variable: T
     Type: float
     Total Size: 5529600 bytes
                 1382400 values
     Number of Dimensions: 4
     Dimensions and sizes:   [time | 60] x [lev 5] x [lat | 48] x [lon | 96]
     Coordinates: 
          time: [2349..4143]
          lev: [850..200]
          lat: [-87.15909..87.15909]
          lon: [ 0..356.25]

Note A: If the file names did not have the .nc extension, then the user could indicate that the files are netCDF by appending the extension via an NCL statement. The actual names of the files on the disk need not be altered.

       fils = systemfunc("ls /model/annual*") +".nc"

Note B: This approach can be used for any supported format: .nc, .grb, .hdf, .hdfeos

Example 2: Same as Example 1 but with the "join" option specified.

     load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl" 
                                     
     fils = systemfunc("ls /model/annual*")
     f    = addfiles(fils, "r")           ; note the "s" of addfile

     ListSetType (f, "join")       

     T    = addfiles_GetVar(f,fils,"T")
     printVarSummary(T)

The output yields:

     Variable: T
     Type: float
     Total Size: 5529600 bytes
                 1382400 values
     Number of Dimensions: 5
     Dimensions and sizes:   [case | 5] x [time | 12] x [lev | 5] x [lat | 48] x [lon
     
     | 96]
     Coordinates:
                 case: [0..4]
                 time: [2349..2683]
                 lev: [850000..200]
                 lat: [-87.15909..87.15909]
                 lon: [ 0..356.25]

     Number Of Attributes: 3
       missing_value :       1e+36
       units :
       long_name :   temperature



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