python - 为什么我会收到类型错误 : float when I try to iterate my list

Question

所以我在这里解决了我有点尴尬的错误:What is happening with my types, TypeError? (Python)

现在我得到了另一个。

我检索数据的方法:

def retrieveSpeeds(databasepath, someid):
     con = lite.connect(databasepath)
     with con:
        cur = con.execute("SELECT speed FROM speeds WHERE id = someid")
        speeds = [x[0] for x in cur]
        for i in range(0, len(speed)):
            newspeeds.append(float(speed[i]))
     return speeds

所以返回看起来像:

[14.0, 14.5, 14.5, 14.5, 14.5, 13.8]

我的主要做法是:

maxspeeds = []
for id in userid:
    speed = retrieveSpeeds(databasepath, id)
    if len(speed)>0:
           maxspeeds.append(max(speed))
for i in range(0,len(maxspeeds)):
    if maxspeeds[i] > 40:
          maxspeeds = maxspeeds.pop(i)

现在我的新问题是:

    Traceback (most recent call last):
    if maxspeeds[i]>40:
    TypeError: 'float' object has no attribute '__getitem__'

怎么突然想到我的list是float对象呢？我还会犯更多错误吗？

Answer 1

您正在将 maxspeeds 分配给 maxspeeds.pop(i) 的输出，它返回一个 number，它是 popped 项目。相反，不要为输出分配任何内容:

maxspeeds = []
for id in userid:
    speed = retrieveSpeeds(databasepath, id)
    if len(speed)>0:
           maxspeeds.append(max(speed))
for i in range(0,len(maxspeeds)):
    if maxspeeds[i] > 40:
          maxspeeds.pop(i) #Here

.pop返回已删除项目的索引，因此当您将列表分配给该输出时，列表成为索引(整数)。