LSSTApplications  20.0.0
LSSTDataManagementBasePackage
cachingSkyMap.py
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1 #
2 # LSST Data Management System
3 # Copyright 2008-2012 LSST Corporation.
4 #
5 # This product includes software developed by the
6 # LSST Project (http://www.lsst.org/).
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21 #
22 
23 __all__ = ["CachingSkyMap"]
24 
25 from .baseSkyMap import BaseSkyMap
26 
27 
29  """A SkyMap that generates its tracts on request and caches them.
30 
31  Parameters
32  ----------
33  numTracts : `int`
34  Number of tracts to create.
35  config : `lsst.skymap.BaseSkyMapConfig` (optional)
36  The configuration for this SkyMap; if None use the default config.
37  version : `int` or `tuple` of `int` (optional)
38  Software version of this class, to retain compatibility with old
39  instances.
40 
41  Notes
42  -----
43  A subclass should define
44  * __init__ to calculate the required number of tracts (and pass it up)
45  * generateTract to generate a tract
46 
47  Subclassers should also check that the arguments to the constructor are
48  consistent with the below __reduce__ method.
49  """
50 
51  def __init__(self, numTracts, config=None, version=0):
52  super(CachingSkyMap, self).__init__(config)
53  self._numTracts = numTracts
54  self._tractCache = [None] * self._numTracts
55  self._tractInfo = None # We shouldn't need this; we will generate tracts on demand
56  self._version = version
57 
58  def __reduce__(self):
59  """To support pickling.
60 
61  Notes
62  -----
63  **Warning:** This method assumes that the constructor is be defined:
64  __init__(self, config, version=defaultVersion)
65  The use of 'config' is effectively set by the registry mechanism.
66  If additional optional arguments are added, this method should be
67  overridden to correspond.
68  """
69  return (self.__class__, (self.config, self._version))
70 
71  def __iter__(self):
72  """Iterator over tracts."""
73  for i in range(self._numTracts):
74  yield self[i]
75 
76  def __len__(self):
77  """Length is number of tracts."""
78  return self._numTracts
79 
80  def __getitem__(self, index):
81  """Get the TractInfo for a particular index.
82 
83  The tract is returned from a cache, if available, otherwise generated
84  on the fly.
85  """
86  if index < 0 or index > self._numTracts:
87  raise IndexError("Index out of range: %d vs %d" % (index, self._numTracts))
88  if self._tractCache[index] is not None:
89  return self._tractCache[index]
90  tract = self.generateTract(index)
91  self._tractCache[index] = tract
92  return tract
93 
94  def generateTract(self, index):
95  """Generate TractInfo for the specified tract index."""
96  raise NotImplementedError("Subclasses must define this method.")
lsst.skymap.cachingSkyMap.CachingSkyMap._tractInfo
_tractInfo
Definition: cachingSkyMap.py:55
lsst.skymap.baseSkyMap.BaseSkyMap.config
config
Definition: baseSkyMap.py:107
lsst.skymap.cachingSkyMap.CachingSkyMap._version
_version
Definition: cachingSkyMap.py:56
lsst.skymap.cachingSkyMap.CachingSkyMap.__init__
def __init__(self, numTracts, config=None, version=0)
Definition: cachingSkyMap.py:51
lsst.skymap.cachingSkyMap.CachingSkyMap.__iter__
def __iter__(self)
Definition: cachingSkyMap.py:71
lsst.skymap.cachingSkyMap.CachingSkyMap.__reduce__
def __reduce__(self)
Definition: cachingSkyMap.py:58
lsst.skymap.cachingSkyMap.CachingSkyMap.__len__
def __len__(self)
Definition: cachingSkyMap.py:76
lsst.skymap.cachingSkyMap.CachingSkyMap
Definition: cachingSkyMap.py:28
lsst.skymap.cachingSkyMap.CachingSkyMap._tractCache
_tractCache
Definition: cachingSkyMap.py:54
lsst.skymap.baseSkyMap.BaseSkyMap
Definition: baseSkyMap.py:75
lsst.skymap.cachingSkyMap.CachingSkyMap._numTracts
_numTracts
Definition: cachingSkyMap.py:53
lsst.skymap.cachingSkyMap.CachingSkyMap.__getitem__
def __getitem__(self, index)
Definition: cachingSkyMap.py:80
lsst.skymap.cachingSkyMap.CachingSkyMap.generateTract
def generateTract(self, index)
Definition: cachingSkyMap.py:94