TEST_OPENDAP - Ferret/PyFerret Documentation

TEST_OPENDAP

TEST_OPENDAP(url)
Returns the status flag from attempt to open an OPeNDAP URL or local NetCDF file.

url: OPeNDAP URL to test (STRING)

A status flag of 0 means successful access.

Arguments:	URL	String, the URL to try
Result Axes:	X	ABSTRACT
	Y	NORMAL
	Z	NORMAL
	T	NORMAL

Examples: First a valid URL. The code for Success is 0.

yes? LIST test_opendap ("http://test.opendap.org/opendap/data/nc/test.nc")
VARIABLE : TEST_OPENDAP ("http://test.opendap.org/opendap/data/nc/test.nc")
X        : 1
0.0000

Here is a test of an invalid URL

yes? LIST test_opendap ("http://not_a_valid_server/test.nc")
VARIABLE : TEST_OPENDAP ("http://not_a_valid_server/test.nc")
X        : 1
1001.

The function may also be run on local files, returning 0 for success and a non-zero flag for failure to open the dataset as a netCDF file, however if the file is not in the current working directory then the specification must include the path on the local file system. (Ferret's "USE" command searches the directories that are included in the FER_DATA environment variable; the TEST_OPENDAP function does not.) It does not operate on file types other than netCDF files.

yes? LIST test_opendap ("myfile.nc")
VARIABLE : TEST_OPENDAP ("myfile.nc")
X        : 1
0.0000
 
yes? LIST test_opendap("this_file_doesnt_exist.nc")
VARIABLE : TEST_OPENDAP("this_file_doesnt_exist.nc")
X : 1
2.000