def __init__(self, valid=None, invalid=None, valid_equivalent=None): ''' Check if variables can be expressed without using variables in invalid. init_valid_equivalent provides a dictionary mapping some invalid variables to valid ones that can be used instead. ''' if valid is None: valid = [] if invalid is None: invalid = [] if valid_equivalent is None: valid_equivalent = OrderedDict() # Nodes that are valid to have in the graph computing outputs self.valid = set(valid) # Nodes that are NOT valid to have in the graph computing outputs self.invalid = set(invalid) # Mapping from invalid variables to equivalent valid ones. self.valid_equivalent = valid_equivalent.copy() self.valid.update(valid_equivalent.values()) self.invalid.update(valid_equivalent.keys())