Problems with Global Variable

Question

I have the following function definition:

def rcsplit(arr):
 if np.all(arr==0): return [] # if all zeros return
 global res
 arr = delrc(arr) # delete leading/trailing rows/cols with all zeros
 indr = np.where(np.all(arr==0,axis=1))[0]
 indc = np.where(np.all(arr==0,axis=0))[0]
 if not indr and not indc: # If no further split possible return
 res.append(arr)
 return
 arr=np.delete(arr,indr,axis=0) #delete empty rows in between non empty rows
 arr=np.delete(arr,indc,axis=1) #delete empty cols in between non empty cols
 arr=np.split(arr,indc,axis=1) # split on empty (all zeros) cols
 arr2=[]
 for i in arr:
 z=delrc(i) 
 arr2.extend(np.split(z,indr,axis=0)) # split on empty (all zeros) rows
 for i in arr2:
 rcsplit(np.array(i))

The problem is I receive the following error:

NameError: global name 'res' is not defined

But this exact code works on other consoles. Is it my Python 2.7?

• Tony Suffolk 66: when do you recieve that error - what is the rest of your code - is there a smaller but complete code segment thatgenerates that error.
• user239546: Why are you trying to use (and declaring) a global variable inside a function?
• alvarezcl: Yes, I noticed that I simply had to define res = [] in order for it to work. Would there be a way I don't have to use a global variable in this recursion?
• martineau: A way to not use a global variable would be to add a res function argument with a default value of None, then in the function check to see if that's its value and initialize it to [] if so. When the function calls itself recursively, pass the current value of res in the call (to override the default value of None).

Answer 1

It seems that the global variable res is not defined before the function, maybe it is defined in the other console.