netcdf4_pydap 0.2.6

netCDF4 and CAS compatibility layer for pydap

This code provides enhancements to the pydap client package:

1. An updated pydap client that uses the requests package to handle Central Authentication Services (such as ESGF).

2. A (partial) compatibility layer with netcdf4-python.

Frederic Laliberte University of Toronto, 2016

Documentation

ESGF

1. Register at https://pcmdi.llnl.gov/user/add/?next=https://pcmdi.llnl.gov/projects/esgf-llnl/. When registering, you will create a password and receive an openid.

2. Go to https://pcmdi.llnl.gov/esg-orp/home.htm and login with your openid using your password.

3. Go to https://pcmdi.llnl.gov/esg-orp/registration-request.htm?resource=http%3A%2F%2Fpcmdi.llnl.gov%2Fthredds%2FfileServer%2Fesg_testroot%2Fregister%2Fcmip5_research.nc. Your browser will likely ask you to trust some certificates. CLICK ALWAYS ALLOW. If you don’t do this, it won’t work.

4. Register for CMIP5 Research. You do not need to download data.

5. Connect to OPeNDAP links as follows:

   import matplotlib.pyplot as plt
   import numpy as np
   
   import netcdf4_pydap
   import netcdf4_pydap.cas.esgf as esgf
   openid = YOUROPENID
   password = YOURPASSWORD
   
   credentials={
                 'password' : password,
                 'authentication_url' : esgf._uri(openid)}
   
   url = ('http://cordexesg.dmi.dk/thredds/dodsC/cordex_general/cordex/'
          'output/EUR-11/DMI/ICHEC-EC-EARTH/historical/r3i1p1/DMI-HIRHAM5/'
          'v1/day/pr/v20131119/'
          'pr_EUR-11_ICHEC-EC-EARTH_historical_r3i1p1_DMI-HIRHAM5_v1_day_19960101-20001231.nc')
   
   with netcdf4_pydap.Dataset(url,**credentials) as dataset:
       data = dataset.variables['pr'][0,:,:]
       plt.contourf(np.squeeze(data))
       plt.show()

6. If using https://ceda.ac.uk instead of https://pcmdi.llnl.gov, your username must be passed along with your credentials use:

   credentials={
                 'username' : YOURCEDAUSERNAME,
                 'password' : password,
                 'authentication_url' : esgf._uri(openid)}

URS NASA Earthdata

There are a few steps required to connect to NASA Earthdata:

1. Create an account at https://urs.earthdata.nasa.gov

2. Authorize the data to see your profile (NASA calls this adding an app, a la Facebook). Follow http://disc.sci.gsfc.nasa.gov/registration/authorizing-desidsc-data-access-in-earthdata_login

3. Load OPeNDAP data:

   import matplotlib.pyplot as plt
   import numpy as np
   import netcdf4_pydap
   
   credentials={'username': YOURUSERNAME,
                'password': YOURPASSWORD,
                'authentication_url':'https://urs.earthdata.nasa.gov/'}
   url = ('http://goldsmr3.gesdisc.eosdis.nasa.gov:80/opendap/'
          'MERRA_MONTHLY/MAIMCPASM.5.2.0/1979/MERRA100.prod.assim.instM_3d_asm_Cp.197901.hdf')
   
   with netcdf4_pydap.Dataset(url, **credentials) as dataset:
       data = dataset.variables['SLP'][0,:,:]
       plt.contourf(np.squeeze(data))
       plt.show()

Version History

0.2.6: Another bug fix when getting cookies.

0.2.5: Bug fix when getting cookies.

0.2.4: Bug fix for ESGF.

0.2.3: New authentication method. Support URS NASA Earthdata

0.2.2: Pydap 3.1.1 is now a requirement.

0.2.1: Removed support for NASA Earthdata.

0.2: Travis-CI integration. Limited test suite. Code reorganization.

0.1.4: Bug fix and more robust error handling.

0.1.1: Added special Dataset class to mimic wget.

0.1 : Initial commit.