IRI data library opendap error from 1.4 to 1.5

[mktippett]

In version 1.5.4

import netCDF4
soi_url_does_NOT_work = 'http://iridl.ldeo.columbia.edu/SOURCES/.Indices/.soi/.c8110/.anomaly/T/%28Jan%201979%29/VALUE/dods'
netCDF4.Dataset(soi_url_does_NOT_work)

fails and gives the error:

---------------------------------------------------------------------------
OSError                                   Traceback (most recent call last)
<ipython-input-1-cb085b0e14b9> in <module>
      1 import netCDF4
      2 soi_url_does_NOT_work = 'http://iridl.ldeo.columbia.edu/SOURCES/.Indices/.soi/.c8110/.anomaly/T/%28Jan%201979%29/VALUE/dods'
----> 3 netCDF4.Dataset(soi_url_does_NOT_work)

netCDF4/_netCDF4.pyx in netCDF4._netCDF4.Dataset.__init__()

netCDF4/_netCDF4.pyx in netCDF4._netCDF4._ensure_nc_success()

OSError: [Errno -90] NetCDF: file not found: b'http://iridl.ldeo.columbia.edu/SOURCES/.Indices/.soi/.c8110/.anomaly/T/%28Jan%201979%29/VALUE/dods'

In version 1.4.2 it does not.

<class 'netCDF4._netCDF4.Dataset'>
root group (NETCDF3_CLASSIC data model, file format DAP2):
    Conventions: IRIDL
    dimensions(sizes): T(1)
    variables(dimensions): >f4 T(T), >f4 anomaly(T)
    groups:

[jswhit]

Nothing has changed in the python interface that would affect this. You probably have linked a different version of netcdf-c. Can you print netCDF4.__netcdf4libversion__ to check this?

[mktippett]

netCDF4.__netcdf4libversion__ is 4.6.2 in the working installation and 4.7.4 in the not working installation.

I should tell my admin who is installing jupyterhub to use libnetcdf=4.6.2 in the yml file? Or something else? (I am very new to this.)

[jswhit]

Here's what ncdump tells me:

jeff-whitakers-imac-9:~/python/netcdf4-python.git] jsw% ncdump -h http://iridl.ldeo.columbia.edu/SOURCES/.Indices/.soi/.c8110/.anomaly/T/%28Jan%201979%29/VALUE/dods
syntax error, unexpected WORD_WORD, expecting SCAN_ATTR or SCAN_DATASET or SCAN_ERROR
context: <html^><title>Error 404 Not Found</title>

Error 404: Page Not Found

Error line: 80 anhtmlserverefize 64000000 defre

Error on line 0 of stdin: interpreter thinks " .from" not defined

Show Current Objects
Ingrid: HTMLwords Indices soi c8110 anomaly[ T |] grid: /T (months since 1960-01-01) ordered (Jan 1951) to (Aug 2020) by 1.0 N= 836 pts :grid grid: /T (months since 1960-01-01) ordered (Jan 1951) to (Aug 2020) by 1.0 N= 836 pts :grid

<textarea name="command" rows="6" cols="50" wrap="soft"> SOURCES .Indices .soi .c8110 .anomaly T %28Jan%201979%29 VALUE</textarea>
1000
ncdump: http://iridl.ldeo.columbia.edu/SOURCES/.Indices/.soi/.c8110/.anomaly/T/%28Jan%201979%29/VALUE/dods: http://iridl.ldeo.columbia.edu/SOURCES/.Indices/.soi/.c8110/.anomaly/T/%28Jan%201979%29/VALUE/dods: NetCDF: file not found

Looks like a server-side issue to me, or an incorrect URL.

[mktippett]

I get

ncdump -h http://iridl.ldeo.columbia.edu/SOURCES/.Indices/.soi/.c8110/.anomaly/T/%28Jan%201979%29/VALUE/dods
netcdf dods {
dimensions:
	T = 1 ;
variables:
	float T(T) ;
		T:standard_name = "time" ;
		T:pointwidth = 1.f ;
		T:expires = 1601942400 ;
		T:calendar = "360" ;
		T:gridtype = 0 ;
		T:units = "months since 1960-01-01" ;
	float anomaly(T) ;
		anomaly:file_missing_value = -999.9f ;
		anomaly:standard_name = "air_pressure_anomaly" ;
		anomaly:history = "Indices Tahiti slp c8110 standardized\n",
			"Indices Tahiti slp c8110 anomaly\n",
			"Averaged over T2[1981, 2010] minimum 0.0% data present\n",
			"sqrt [   total ( { Indices Tahiti slp c8110 anomaly } squared )   / 360. ]\n",
			"  total [ ( Indices Tahiti slp c8110 anomaly ) squared ]   / 360.\n",
			"Averaged over T2[1981, 2010] minimum 0.0% data present\n",
			"Averaged over T[Jan 1981, Dec 2010] minimum 0.0% data present\n",
			"Indices Darwin slp c8110 standardized\n",
			"Indices Darwin slp c8110 anomaly\n",
			"Averaged over T2[1981, 2010] minimum 0.0% data present\n",
			"sqrt [   total ( { Indices Darwin slp c8110 anomaly } squared )   / 360. ]\n",
			"  total [ ( Indices Darwin slp c8110 anomaly ) squared ]   / 360.\n",
			"Averaged over T2[1981, 2010] minimum 0.0% data present\n",
			"Averaged over T[Jan 1981, Dec 2010] minimum 0.0% data present" ;
		anomaly:units = "unitless" ;
		anomaly:expires = 1601942400 ;
		anomaly:long_name = "sea level pressure anomaly" ;
		anomaly:missing_value = -999.9f ;

// global attributes:
		:Conventions = "IRIDL" ;
}

Of course, my ncdump is ancient.

netcdf library version 4.3.3.1 of Feb 22 2016 16:36:46 $

[jswhit]

I would suggest asking on the netcdf-c [issue tracker] (https://github.com/Unidata/netcdf-c/issues) why ncdump works for this URL for older versions of the netcdf-c, but not for 4.7.x.

[mktippett]

Thanks I will do that! (I am assuming that I should close this issue since it is a netcdf-c issue?)

[DennisHeimbigner]

See here:
Unidata/netcdf-c#1832 (comment)