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:
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
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.
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)
TypeError: 'function' object has no attribute '__getitem__'
It appears you have forgotten a pair of parentheses:
a = makeGrid(dim)
What you have now:
a = makeGrid
just aliases the makeGrid
function instead of calling it. Then, when you try to index into a
, like so:
a[i]
it's trying to index into a function, which does not have the __getitem__
magic method needed for indexing with bracket notation.
You're not calling makeGrid()
, you're assigning the function object itself to a
:
a = makeGrid(dim)
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With