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isfilepresent

Checks if a file exists.

Prototype

	function isfilepresent (
		file_path  : string   
	)

	return_val [dimsizes(file_path)] :  logical

Arguments

file_path

A scalar string or a multi-dimensional array of strings containing the full or relative path to data files (Unix pathname string) for which to check presence on the filesystem.

Return value

The output of isfilepresent is a logical variable with the same dimension sizes as the input.

Description

The function isfilepresent returns True for every element of file_path that is present on the filesystem, and False if not.

See Also

isfile

Examples

Example 1

The following code will determine if a HDF file named test.hdf exists: 

  if (isfilepresent("test.hdf"))
    f = addfile ("test.hdf", "r")
  end if

Example 2

The following code will determine if each of a group of files exists: 

; specify data directory and get a list of all nc files in the directory
  datadir = getenv("NCARG_ROOT") + "/lib/ncarg/data/cdf/"
  ncdf    = systemfunc("cd "+datadir; "ls *.nc")

; list of files to check 
  fils = (/ "bogus.nc" , "ex01B1_uv300.hs.nc", "foo.nc", "sst30e_netcdf.nc"/)

; Which of "fils" is present
  fils_tf  = isfilepresent(datadir+fils)

  print (fils_tf)
Output: 
Variable: fils_tf
Type: logical
Total Size: 16 bytes
            4 values
Number of Dimensions: 1
Dimensions and sizes:   [4]
Coordinates: 
(0)     False
(1)     True
(2)     False
(3)     True

Example 3

Here's an example that shows how to access a file being served by an OPeNDAP server, and to test if your version of NCL has OPeNDAP capability built into it: 

begin
; The URL is so long, break it into two pieces.
  url      = "http://www.cdc.noaa.gov/cgi-bin/nph-nc/Datasets/"
  filename = "ncep.reanalysis.dailyavgs/pressure/air.1948.nc"

  exists = isfilepresent(url+filename)
  if(.not.exists) then
    print("OPeNDAP test unsuccessful.")
    print("Either the file doesn't exist, or NCL does")
    print("not have OPeNDAP cabilities on this system.")
  else
    f = addfile(url + filename,"r")
    variables = getfilevarnames(f)
    print(variables)     ; should be (/"air","time","lon","lat","level"/)
  end if
end