Source Code for Module gavo.grammars.cdfgrammar

 1  """ 
 2  A grammar wrapping spacepy to parse files in the Common Data Format (CDF), 
 3  http://cdf.gsfc.nasa.gov. 
 4  """ 
 5   
 6  #c Copyright 2008-2019, the GAVO project 
 7  #c 
 8  #c This program is free software, covered by the GNU GPL.  See the 
 9  #c COPYING file in the source distribution. 
10   
11   
12  from gavo import base 
13  from gavo.grammars.common import Grammar, RowIterator, MapKeys 
14   
15   
16 -class CDFHeaderIterator(RowIterator): 
17          """an iterator for headers of CDF files. 
18          """ 
19 -        def _iterRows(self): 
20                  try: 
21                          from spacepy import pycdf 
22                  except ImportError: 
23                          raise base.ui.logOldExc( 
24                                  base.ReportableError("cdfHeaderGrammar needs the external" 
25                                          " spacepy package.  You can obtain it from" 
26                                          " http://spacepy.lanl.gov.")) 
27                   
28                  cdfStruct = pycdf.CDF(self.sourceToken) 
29   
30                  res = {} 
31                  for key, value in cdfStruct.attrs.iteritems(): 
32                          if self.grammar.autoAtomize and value.max_idx()==0: 
33                                  res[key] = value[0] 
34                          else: 
35                                  res[key] = value[:] 
36                  yield res 
37   
38   
39 -class CDFHeaderGrammar(Grammar): 
40          """A grammar that returns the header dictionary of a CDF file 
41          (global attributes). 
42   
43          This grammar yields a single dictionary per file, which corresponds 
44          to the global attributes.  The values in this dictionary may have 
45          complex structure; in particular, sequences are returned as lists. 
46   
47          To use this grammar, additional software is required that (by 2014) 
48          is not packaged for Debian.  See 
49          https://pythonhosted.org/SpacePy/install.html 
50          for installation  
51          instructions.  Note that you must install the CDF library itself as 
52          described further down on that page; the default installation  
53          instructions do not install the library in a public place, so if 
54          you use these, you'll have to set CDF_LIB to the right value, too, 
55          before running dachs imp. 
56          """ 
57          name_ = "cdfHeaderGrammar" 
58   
59          _mapKeys = base.StructAttribute("mapKeys", childFactory=MapKeys, 
60                  default=None, copyable=True, description="Prescription for how to" 
61                  " map labels keys to grammar dictionary keys") 
62          _autoAtomize = base.BooleanAttribute("autoAtomize", 
63                  default=False, copyable=True, description="Unpack 1-element" 
64                  " lists to their first value.") 
65   
66   
67          rowIterator = CDFHeaderIterator 
68   
69 -        def onElementComplete(self): 
70                  if self.mapKeys is None: 
71                          self.mapKeys = base.makeStruct(MapKeys) 
72                  self._onElementCompleteNext(CDFHeaderGrammar) 
73