Initial revision

intern/python/modules/mcf/utils/dictbool.py

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+'''
+DictBool:
+Simplistic (and slow) implementation of Boolean operations for
+dictionaries... really these should be implemented in C, but I
+can't do that till I have MSVC++, which I don't really want to
+buy... this will have to do in the meantime.
+
+>>> from mcf.utils import dictbool
+
+>>> a = {1:2}; b = {2:3}; c={4:5,6:7,8:9,1:5}
+
+>>> dictbool.union(a,b,c) # overwrite a with b and the result with c
+
+{1: 5, 2: 3, 4: 5, 8: 9, 6: 7}
+
+>>> dictbool.collectunion(a,b,c) # collect all possible for each key
+
+{1: [2, 5], 2: [3], 4: [5], 8: [9], 6: [7]}
+
+>>> dictbool.intersect(a,b,c) # no common elements in all three
+
+{}
+
+>>> dictbool.intersect(a,c) # one element is common to both
+
+{1: [2, 5]}
+'''
+
+def union(*args):
+	'''
+	Build a new dictionary with the key,val from all args,
+	first overwritten by second, overwritten by third etc. 
+	Rewritten for Python 1.5 on 98.03.31
+	'''
+	temp = {}
+	for adict in args:
+		# following is the 1.5 version
+		temp.update(adict)
+#		for key,val in adict.items():
+#			temp[key] = val
+	return temp
+
+def collectunion(*args):
+	'''
+	As union, save instead of overwriting, all vals are
+	returned in lists, and duplicates are appended to those
+	lists.
+	'''
+	temp = {}
+	for adict in args:
+		for key,val in adict.items():
+			try:
+				temp[key].append(val)
+			except KeyError:
+				temp[key] = [val]
+	return temp
+
+def intersect(*args):
+	'''
+	Build a new dictionary with those keys common to all args,
+	the vals of the new dict are lists of length len(args), where
+	list[ind] is the value of args[ind] for that key.
+	'''
+	args = map(lambda x: (len(x),x), args)
+	args.sort()
+	temp = {}
+	master = args[0][1]
+	rest = map(lambda x: x[1], args[1:])
+	for var,val in master.items():
+		tempval = [val]
+		for slave in rest:
+			try:
+				tempval.append(slave[var])
+			except KeyError:
+				tempval = None
+				break
+		if tempval:
+			temp[var] = tempval
+	return temp
+