variation.py 文件源码

def is_valid_program(self,p):
        """checks whether program p makes a syntactically valid tree.

        checks that the accumulated program length is always greater than the
        accumulated arities, indicating that the appropriate number of arguments is
        alway present for functions. It then checks that the sum of arties +1
        exactly equals the length of the stack, indicating that there are no
        missing arguments.
        """
        # print("p:",p)
        arities = list(a.arity[a.in_type] for a in p)
        accu_arities = list(accumulate(arities))
        accu_len = list(np.arange(len(p))+1)
        check = list(a < b for a,b in zip(accu_arities,accu_len))
        # print("accu_arities:",accu_arities)
        # print("accu_len:",accu_len)
        # print("accu_arities < accu_len:",accu_arities<accu_len)
        return all(check) and sum(a.arity[a.in_type] for a in p) +1 == len(p) and len(p)>0