Python 类型错误：“函数”对象没有属性“__getitem__”
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TypeError: 'function' object has no attribute '__getitem__'
提问by user1887919
Writing some code in python to evaluate a basic function. I've got a 2d array with some values and I want to apply the function to each of those values and get a new 2-d array:
在 python 中编写一些代码来评估基本功能。我有一个带有一些值的二维数组，我想将该函数应用于每个值并获得一个新的二维数组：
import numpy as N
def makeGrid(dim):
''' Function to return a grid of distances from the centre of an array.
This version uses loops to fill the array and is thus slow.'''
tabx = N.arange(dim) - float(dim/2.0) + 0.5
taby = N.arange(dim) - float(dim/2.0) + 0.5
grid = N.zeros((dim,dim), dtype='float')
for y in range(dim):
for x in range(dim):
grid[y,x] = N.sqrt(tabx[x]**2 + taby[y]**2)
return grid
import math
def BigGrid(dim):
l= float(raw_input('Enter a value for lambda: '))
p= float(raw_input('Enter a value for phi: '))
a = makeGrid
b= N.zeros ((10,10),dtype=float) #Create an array to take the returned values
for i in range(10):
for j in range (10):
b[i][j] = a[i][j]*l*p
return b
if __name__ == "__main__":
''' Module test code '''
size = 10 #Dimension of the array
newGrid = BigGrid(size)
newGrid = N.round(newGrid, decimals=2)
print newGrid
But all i get is the error message
但我得到的只是错误信息
Traceback (most recent call last):
File "sim.py", line 31, in <module>
newGrid = BigGrid(size)
File "sim.py", line 24, in BigGrid
b[i][j] = a[i][j]*l*p
TypeError: 'function' object has no attribute '__getitem__'
Please help.
请帮忙。
回答by Matt Ball
It appears you have forgotten a pair of parentheses:
看来您忘记了一对括号：
a = makeGrid(dim)
What you have now:
你现在拥有的：
a = makeGrid
just aliases the makeGridfunction instead of calling it. Then, when you try to index into a, like so:
只是给makeGrid函数取别名而不是调用它。然后，当您尝试对 进行索引时a，如下所示：
a[i]
it's trying to index into a function, which does not have the __getitem__magic methodneeded for indexing with bracket notation.
它试图对一个函数进行索引，该函数没有使用括号表示法进行索引所需的魔法方法。__getitem__
回答by NPE
You're not calling makeGrid(), you're assigning the function object itself to a:
您不是在调用makeGrid()，而是将函数对象本身分配给a：
a = makeGrid(dim)
回答by Cameron Sparr
As others have said, you need to call makeGrid properly.... just as an fyi, this is a fairly common error to see in Python, and it generally means that your variable is not the type that you thought it was (in this case, you were expecting a matrix, but got a function)
正如其他人所说，您需要正确调用 makeGrid .... 仅供参考，这是在 Python 中看到的一个相当常见的错误，它通常意味着您的变量不是您认为的类型（在此情况，你期待一个矩阵，但得到了一个函数）
TypeError: 'function' object has no attribute '__getitem__'
