title: How do I use pydap library to collect THREDDS data?
body: <p>I have been trying to use the example get_nomads.py module from Will Holgren which he was nice enough to forward my way. In the code, there is a call to get the THREDDS data as follows:</p>
  
  <pre><code>from pydap.client import open_url
  dataset = open_url('https://nomads.ncdc.noaa.gov/thredds/dodsC/gfs-004/201612/20161201/gfs_4_20161201_0000_003.grb2')
  </code></pre>
  
  <p>Which does not work because (apparently) the old THREDDS server has been decommissioned.</p>
  
  <pre><code>Traceback (most recent call last):
    File "C:\Program Files\JetBrains\PyCharm 2018.2.4\helpers\pydev\_pydevd_bundle\pydevd_exec2.py", line 3, in Exec
      exec(exp, global_vars, local_vars)
    File "&lt;input&gt;", line 1, in &lt;module&gt;
    File "C:\Users\pmoran\jira\slf\venv\lib\site-packages\pydap\client.py", line 64, in open_url
      dataset = DAPHandler(url, application, session, output_grid).dataset
    File "C:\Users\pmoran\jira\slf\venv\lib\site-packages\pydap\handlers\dap.py", line 51, in __init__
      raise_for_status(r)
    File "C:\Users\pmoran\jira\slf\venv\lib\site-packages\pydap\net.py", line 30, in raise_for_status
      comment=response.body
  webob.exc.HTTPError: 404 Not Found
  </code></pre>
  
  <p>So looking around I am not able to find a THREDDS server that supports this method of data access.</p>
  
  <p>BTW: I am able to get data as follows:</p>
  
  <pre><code>url = 'http://dtvirt5.deltares.nl:8080/thredds/dodsC/opendap/rijkswaterstaat/jarkus/profiles/transect.nc'
  dataset = open_url(url)
  &lt;DatasetType with children 'id', 'areacode', 'areaname', 'alongshore', 'cross_shore', 'time', 'time_bounds', 'epsg', 'x', 'y', 'lat', 'lon', 'angle', 'mean_high_water', 'mean_low_water', 'max_cross_shore_measurement', 'min_cross_shore_measurement', 'nsources', 'max_altitude_measurement', 'min_altitude_measurement', 'rsp_x', 'rsp_y', 'rsp_lat', 'rsp_lon', 'time_topo', 'time_bathy', 'origin', 'altitude'&gt;
  variable = dataset['id']
  print(variable[0:10])
  [2000100 2000101 2000102 2000103 2000104 2000105 2000106 2000120 2000140
   2000160]
  </code></pre>
  
  <p>I also see that I can manually download the data from <a href="https://www.ncei.noaa.gov/thredds/dodsC/gfs-g4-anl-files/201808/20180828/gfsanl_4_20180828_1800_006.grb2.html" rel="nofollow noreferrer">https://www.ncei.noaa.gov/thredds/dodsC/gfs-g4-anl-files/201808/20180828/gfsanl_4_20180828_1800_006.grb2.html</a></p>
  
  <p>But I cant seem to find argument format to download the data using pydap. I think all I need is a pointer to a real THREDDS server that has the appropriate DDS and DAS files at the same URI location.</p>
  
  <p>Does anyone know how to get the GFS4 GRB files using the pydap client?</p>
  
  <p>Thanks</p>