Python TypeErrors："‘list’对象不可调用“和"'function‘对象不可订阅”
Python TypeErrors："‘list’对象不可调用“和"'function‘对象不可订阅”
提问于 2012-06-30 04:18:26
我有以下代码：
from random import randint,choice
add=lambda x:lambda y:x+y
sub=lambda x:lambda y:x-y
mul=lambda x:lambda y:x*y
ops=[[add,'+'],[sub,'-'],[mul,'*']]
def gen_expression(length,left,right):
expr=[]
for i in range(length):
op=choice(ops)
expr.append([op[0](randint(left,right)),op[1]])
return expr
def eval_expression (expr,x):
for i in expr:
x=i[0](x)
return x
def eval_expression2 (expr,x):
for i in expr:
x=i(x)
return x
[snip , see end of post]
def genetic_arithmetic(get,start,length,left,right):
batch=[]
found = False
for i in range(30):
batch.append(gen_expression(length,left,right))
while not found:
batch=sorted(batch,key=lambda y:abs(eval_expression(y,start)-get))
print evald_expression_tostring(batch[0],start)+"\n\n"
#combine
for w in range(len(batch)):
rind=choice(range(length))
batch.append(batch[w][:rind]+choice(batch)[rind:])
#mutate
for w in range(len(batch)):
rind=choice(range(length))
op=choice(ops)
batch.append(batch[w][:rind]+[op[0](randint(left,right)),op[1]]+batch[w][rind+1:])
found=(eval_expression(batch[0],start)==get)
print "\n\n"+evald_expression_tostring(batch[0],start)当我尝试调用以eval_expression作为排序关键字的genetic_artihmetic时，得到的结果如下：
Traceback (most recent call last):
File "<pyshell#113>", line 1, in <module>
genetic_arithmetic(0,10,10,-10,10)
File "/home/benikis/graming/py/genetic_number.py", line 50, in genetic_arithmetic
batch=sorted(batch,key=lambda y:abs(eval_expression(y,start)-get))
File "/home/benikis/graming/py/genetic_number.py", line 50, in <lambda>
batch=sorted(batch,key=lambda y:abs(eval_expression(y,start)-get))
File "/home/benikis/graming/py/genetic_number.py", line 20, in eval_expression
x=i[0](x)
TypeError: 'function' object is unsubscriptable当我尝试使用eval_expression2作为排序时，错误是这样的：
Traceback (most recent call last):
File "<pyshell#114>", line 1, in <module>
genetic_arithmetic(0,10,10,-10,10)
File "/home/benikis/graming/py/genetic_number.py", line 50, in genetic_arithmetic
batch=sorted(batch,key=lambda y:abs(eval_expression2(y,start)-get))
File "/home/benikis/graming/py/genetic_number.py", line 50, in <lambda>
batch=sorted(batch,key=lambda y:abs(eval_expression2(y,start)-get))
File "/home/benikis/graming/py/genetic_number.py", line 25, in eval_expression2
x=i(x)
TypeError: 'list' object is not callable据我所知，我猜想sorted()正试图递归排序子列表？这到底是怎么回事？
Python版本是2.6 - debian稳定代码库中的版本。
截图如下：
def expression_tostring(expr):
expr_str=len(expr)*'('+'x '
for i in expr :
if i[1]=='*':
n=i[0](1)
else:
n=i[0](0)
expr_str+=i[1]+' '+str(n)+') '
return expr_str
def evald_expression_tostring(expr,x):
exprstr=expression_tostring(expr).replace('x',str(x))
return exprstr+ ' = ' + str(eval_expression(expr,x))回答 2
Stack Overflow用户
回答已采纳
发布于 2012-06-30 04:24:21
x=i[0](x) #here i is a function so you can't perform indexing operation on it
x=i(x) #here i is a list so you can't call it as a function在这两种情况下，i的值都是从expr中获取的，可能是expr包含的对象类型与您在这里假设的不同。
Stack Overflow用户
发布于 2012-06-30 04:33:32
尝试以下修改：
def gen_expression(length,left,right):
expr=[]
for i in range(length):
op=choice(ops)
expr.append([op[0], randint(left,right),op[1]])
return expr
def eval_expression (expr,x):
for i in expr:
x=i[0](i[1])
return x您有expr.append([op[0](randint(left,right)),op[1]])，它将把调用函数的返回值放到第0个索引中。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/11268429
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