/[escript]/trunk/escript/py_src/util.py
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revision 492 by gross, Fri Feb 3 02:07:24 2006 UTC revision 517 by gross, Tue Feb 14 02:25:02 2006 UTC
# Line 828  class Symbol(object): Line 828  class Symbol(object):
828         """         """
829         return power(other,self)         return power(other,self)
830    
831       def __getitem__(self,index):
832           """
833           returns the slice defined by index
834    
835           @param index: defines a
836           @type index: C{slice} or C{int} or a C{tuple} of them
837           @return: a S{Symbol} representing the slice defined by index
838           @rtype: L{DependendSymbol}
839           """
840           return GetSlice_Symbol(self,index)
841    
842  class DependendSymbol(Symbol):  class DependendSymbol(Symbol):
843     """     """
844     DependendSymbol extents L{Symbol} by modifying the == operator to allow two instances to be equal.     DependendSymbol extents L{Symbol} by modifying the == operator to allow two instances to be equal.
# Line 878  class DependendSymbol(Symbol): Line 889  class DependendSymbol(Symbol):
889  #=========================================================  #=========================================================
890  #  Unary operations prserving the shape  #  Unary operations prserving the shape
891  #========================================================  #========================================================
892    class GetSlice_Symbol(DependendSymbol):
893       """
894       L{Symbol} representing getting a slice for a L{Symbol}
895       """
896       def __init__(self,arg,index):
897          """
898          initialization of wherePositive L{Symbol} with argument arg
899          @param arg: argument
900          @type arg: L{Symbol}.
901          @param index: defines index
902          @type index: C{slice} or C{int} or a C{tuple} of them
903          @raises IndexError: if length of index is larger than rank of arg or a index start or stop is out of range
904          @raises ValueError: if a step is given
905          """
906          if not isinstance(index,tuple): index=(index,)
907          if len(index)>arg.getRank():
908               raise IndexError,"GetSlice_Symbol: index out of range."
909          sh=()
910          index2=()
911          for i in range(len(index)):
912             ix=index[i]
913             if isinstance(ix,int):
914                if ix<0 or ix>=arg.getShape()[i]:
915                   raise ValueError,"GetSlice_Symbol: index out of range."
916                index2=index2+(ix,)
917             else:
918               if not ix.step==None:
919                 raise ValueError,"GetSlice_Symbol: steping is not supported."
920               if ix.start==None:
921                  s=0
922               else:
923                  s=ix.start
924               if ix.stop==None:
925                  e=arg.getShape()[i]
926               else:
927                  e=ix.stop
928                  if e>arg.getShape()[i]:
929                     raise IndexError,"GetSlice_Symbol: index out of range."
930               index2=index2+(slice(s,e),)
931               if e>s:
932                   sh=sh+(e-s,)
933               elif s>e:
934                   raise IndexError,"GetSlice_Symbol: slice start must be less or equal slice end"
935          for i in range(len(index),arg.getRank()):
936              index2=index2+(slice(0,arg.getShape()[i]),)
937              sh=sh+(arg.getShape()[i],)
938          super(GetSlice_Symbol, self).__init__(args=[arg,index2],shape=sh,dim=arg.getDim())
939    
940       def getMyCode(self,argstrs,format="escript"):
941          """
942          returns a program code that can be used to evaluate the symbol.
943    
944          @param argstrs: gives for each argument a string representing the argument for the evaluation.
945          @type argstrs: C{str} or a C{list} of length 1 of C{str}.
946          @param format: specifies the format to be used. At the moment only "escript" ,"text" and "str" are supported.
947          @type format: C{str}
948          @return: a piece of program code which can be used to evaluate the expression assuming the values for the arguments are available.
949          @rtype: C{str}
950          @raise: NotImplementedError: if the requested format is not available
951          """
952          if format=="escript" or format=="str"  or format=="text":
953             return "%s.__getitem__(%s)"%(argstrs[0],argstrs[1])
954          else:
955             raise NotImplementedError,"GetItem_Symbol does not provide program code for format %s."%format
956    
957       def substitute(self,argvals):
958          """
959          assigns new values to symbols in the definition of the symbol.
960          The method replaces the L{Symbol} u by argvals[u] in the expression defining this object.
961    
962          @param argvals: new values assigned to symbols
963          @type argvals: C{dict} with keywords of type L{Symbol}.
964          @return: result of the substitution process. Operations are executed as much as possible.
965          @rtype: L{escript.Symbol}, C{float}, L{escript.Data}, L{numarray.NumArray} depending on the degree of substitution
966          @raise TypeError: if a value for a L{Symbol} cannot be substituted.
967          """
968          if argvals.has_key(self):
969             arg=argvals[self]
970             if self.isAppropriateValue(arg):
971                return arg
972             else:
973                raise TypeError,"%s: new value is not appropriate."%str(self)
974          else:
975             args=self.getSubstitutedArguments(argvals)
976             arg=args[0]
977             index=args[1]
978             return arg.__getitem__(index)
979    
980  def log10(arg):  def log10(arg):
981     """     """
982     returns base-10 logarithm of argument arg     returns base-10 logarithm of argument arg

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