On 08/14/2015 03:15 PM, Jason Swails wrote:
On Aug 14, 2015, at 3:18 AM, Tom P <werot...@freent.dd> wrote:
Thanks for the reply but that is not what the documentation says.
http://unidata.github.io/netcdf4-python/#section8
"Remote OPeNDAP-hosted datasets can be accessed for reading over http if a URL
is provided to the netCDF4.Dataset constructor instead of a filename. However, this
requires that the netCDF library be built with OPenDAP support, via the --enable-dap
configure option (added in version 4.0.1).”
Huh, so it does. Your error message says "file not found", though, which
suggested to me that it's trying to interpret the NetCDF file as a local file instead of
a URL. Indeed, when I run that example, the traceback is more complete (the traceback
you printed had omitted some information):
netCDF4.Dataset('http://www1.ncdc.noaa.gov/pub/data/cmb/ersst/v3b/netcdf/ersst.201507.nc')
syntax error, unexpected WORD_WORD, expecting SCAN_ATTR or SCAN_DATASET or
SCAN_ERROR
context: <!DOCTYPE^ HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><html><head><title>404 Not
Found</title></head><body><h1>Not Found</h1><p>The requested URL /pub/data/cmb/ersst/v3b/netcdf/ersst.201507.nc.dds was not found
on this server.</p></body></html>
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "netCDF4/_netCDF4.pyx", line 1547, in netCDF4._netCDF4.Dataset.__init__
(netCDF4/_netCDF4.c:9551)
RuntimeError: NetCDF: file not found
So it’s clear that netCDF4 is at least *trying* to go online to look for the file,
but it simply can’t find it. Since the docs say it’s linking to libcurl, I tried
using curl to download the file (curl -#
http://www1.ncdc.noaa.gov/pub/data/cmb/ersst/v3b/netcdf/ersst.201507.nc >
test.nc) and it worked fine. What’s more, it *seems* like the file
(/pub/.../ersst.201507.nc.dds) was decorated with the ‘.dds’ suffix for some
reason (not sure if the server redirected the request there or not). But this
looks like a netCDF4 issue. Perhaps you can go to their project page on Github
and file an issue there -- they will be more likely to have your answer than
people here.
HTH,
Jason
Hi,
yes the file does appear to be there, I can download it and I can
open and read the URL using urllib. Since there are a whole bunch of
files in the directory, I really need MFDataset, but according to the
documentation that doesn't work with URLs. Maybe the solution really is
to D/L them all into a temporary folder and use MFDataset.
and for the Anaconda package -
http://docs.continuum.io/anaconda/changelog
"2013-05-08: 1.5.0:
Highlights:
updates to all important packages: python, numpy, scipy, ipython, matplotlib,
pandas, cython
added netCDF4 (with OpenDAP support) on Linux and MacOSX"
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Jason M. Swails
BioMaPS,
Rutgers University
Postdoctoral Researcher
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