lsst.daf.butlerUtils.fsScanner.FsScanner Class Reference

Inheritance diagram for lsst.daf.butlerUtils.fsScanner.FsScanner:

Public Member Functions
def	__init__
def	getFields
def	isNumeric
def	isInt
def	isFloat
def	processPath

Public Attributes
	globString
	fields
	reString

Detailed Description

Class to scan a filesystem location for paths matching a template.

Decomposes the resulting paths into fields and passes them to a callback
function.

Definition at line 33 of file fsScanner.py.

Constructor & Destructor Documentation

def lsst.daf.butlerUtils.fsScanner.FsScanner.__init__	(		self,
			pathTemplate
	)

Constructor.  Takes the path template, which should be in the form
of a Python string with named format substitution specifications.
Such a template would be suitable for generating a path given a set of
fields in a dictionary.  Does not handle hex (%x or %X).

Example:
    %(field)s/%(visit)d/%(exposure)d/raw-%(visit)d-e%(exposure)03d-c%(ccd)03d-a%(amp)03d.fits
    
Note that fields may appear multiple times; the second and subsequent
appearances of such fields will have "_{number}" appended to them to
disambiguate, although it is typically assumed that they will all be
identical.

Definition at line 40 of file fsScanner.py.

    def __init__(self, pathTemplate):
        """Constructor.  Takes the path template, which should be in the form
        of a Python string with named format substitution specifications.
        Such a template would be suitable for generating a path given a set of
        fields in a dictionary.  Does not handle hex (%x or %X).
        
        Example:
            %(field)s/%(visit)d/%(exposure)d/raw-%(visit)d-e%(exposure)03d-c%(ccd)03d-a%(amp)03d.fits
            
        Note that fields may appear multiple times; the second and subsequent
        appearances of such fields will have "_{number}" appended to them to
        disambiguate, although it is typically assumed that they will all be
        identical.
        """

        # Change template into a globbable path specification.
        fmt = re.compile(r'%\((\w+)\).*?([dioueEfFgGcrs])')
        self.globString = fmt.sub('*', pathTemplate)

        # Change template into a regular expression.
        last = 0
        self.fields = {}
        self.reString = ""
        n = 0
        pos = 0
        for m in fmt.finditer(pathTemplate):
            fieldName = m.group(1)
            if self.fields.has_key(fieldName):
                fieldName += "_%d" % (n,)
                n += 1

            prefix = pathTemplate[last:m.start(0)]
            last = m.end(0)
            self.reString += prefix
        
            if m.group(2) in 'crs':
                fieldType = str
                self.reString += r'(?P<' + fieldName + '>.+?)'
            elif m.group(2) in 'eEfFgG':
                fieldType = float
                self.reString += r'(?P<' + fieldName + '>[\d.eE+-]+?)'
            else:
                fieldType = int
                self.reString += r'(?P<' + fieldName + '>[\d+-]+?)'

            self.fields[fieldName] = dict(pos=pos, fieldType=fieldType)
            pos += 1

        self.reString += pathTemplate[last:]