chain.Chain Class Reference

Inheritance diagram for chain.Chain:

Public Member Functions
def	__getattr__ (self, attr)
def	__getitem__ (self, index)
def	__init__ (self, input, tree_name=None)
def	__iter__ (self)
def	__len__ (self)

Public Attributes
	chain
	files

Private Member Functions
def	_guessTreeName (self, pattern)

Detailed Description

Wrapper to TChain, with a python iterable interface.

Example of use:  #TODO make that a doctest / nose?
   from chain import Chain
   the_chain = Chain('../test/test_*.root', 'test_tree')
   event3 = the_chain[2]
   print event3.var1

   for event in the_chain:
       print event.var1

Definition at line 22 of file chain.py.

Constructor & Destructor Documentation

def chain.Chain.__init__	(		self,
			input,
			tree_name = None
	)

Create a chain.

Parameters:
  input     = either a list of files or a wildcard (e.g. 'subdir/*.root').
      In the latter case all files matching the pattern will be used
      to build the chain.
  tree_name = key of the tree in each file.
      if None and if each file contains only one TTree,
      this TTree is used.

Definition at line 35 of file chain.py.

    def __init__(self, input, tree_name=None):
        """
        Create a chain.

        Parameters:
          input     = either a list of files or a wildcard (e.g. 'subdir/*.root').
                      In the latter case all files matching the pattern will be used
                      to build the chain.
          tree_name = key of the tree in each file.
                      if None and if each file contains only one TTree,
                      this TTree is used.
        """
        self.files = input
        if isinstance(input, str): # input is a pattern
            self.files = glob.glob(input)
            if len(self.files)==0:
                raise ValueError('no matching file name: '+input)
        else: # case of a list of files
            if False in [
                ((is_pfn(fnam) and os.path.isfile(fnam)) or
                is_lfn(fnam)) or is_rootfn(fnam)
                for fnam in self.files]:
                err = 'at least one input file does not exist\n'
                err += pprint.pformat(self.files)
                raise ValueError(err)
        if tree_name is None:
            tree_name = self._guessTreeName(input)
        self.chain = TChain(tree_name)
        for file in self.files:
            self.chain.Add(file)

Member Function Documentation

def chain.Chain.__getattr__	(		self,
			attr
	)

All functions of the wrapped TChain are made available

Definition at line 92 of file chain.py.

References edm::FileLocator::Rule.chain, and chain.Chain.chain.

    def __getattr__(self, attr):
        """
        All functions of the wrapped TChain are made available
        """
        return getattr(self.chain, attr)

def chain.Chain.__getitem__	(		self,
			index
	)

Returns the event at position index.

Definition at line 104 of file chain.py.

References edm::FileLocator::Rule.chain, and chain.Chain.chain.

    def __getitem__(self, index):
        """
        Returns the event at position index.
        """
        self.chain.GetEntry(index)
        return self.chain

def chain.Chain.__iter__

(

self

)

Definition at line 98 of file chain.py.

References edm::FileLocator::Rule.chain, and chain.Chain.chain.

    def __iter__(self):
        return iter(self.chain)

def chain.Chain.__len__

(

self

)

Definition at line 101 of file chain.py.

References createfilelist.int.

    def __len__(self):
        return int(self.chain.GetEntries())

def chain.Chain._guessTreeName (   self,   pattern  )

private

Find the set of keys of all TTrees in all files matching pattern.
If the set contains only one key
  Returns: the TTree key
else raises ValueError.

Definition at line 66 of file chain.py.

References readConfig.fileINI.files, chain.Chain.files, MatrixReader.MatrixReader.files, MatrixUtil.InputInfo.files, JsonOutputProducer::JsonConfigurationBlock.files, join(), and list().

    def _guessTreeName(self, pattern):
        """
        Find the set of keys of all TTrees in all files matching pattern.
        If the set contains only one key
          Returns: the TTree key
        else raises ValueError.
        """
        names = []
        for fnam in self.files:
            rfile = TFile(fnam)
            for key in rfile.GetListOfKeys():
                obj = rfile.Get(key.GetName())
                if isinstance(obj, TTree):
                    names.append( key.GetName() )
        thename = set(names)
        if len(thename)==1:
            return list(thename)[0]
        else:
            err = [
                'several TTree keys in {pattern}:'.format(
                    pattern=pattern
                    ),
                ','.join(thename)
                ]
            raise ValueError('\n'.join(err))

Member Data Documentation

chain.Chain.chain

Definition at line 62 of file chain.py.

Referenced by chain.Chain.__getattr__(), chain.Chain.__getitem__(), chain.Chain.__iter__(), chain_test.ChainTestCase.test_get(), chain_test.ChainTestCase.test_guess_treename(), chain_test.ChainTestCase.test_iterate(), and chain_test.ChainTestCase.test_load_1().

chain.Chain.files

Definition at line 47 of file chain.py.

Referenced by chain.Chain._guessTreeName(), dataset.BaseDataset.listOfFiles(), dataset.BaseDataset.listOfGoodFiles(), and dataset.BaseDataset.printFiles().

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