"cannot access local variable 'a' where it is not associated with a value", but the value is defined

The error message "cannot access local variable 'a' where it is not associated with a value" in Python occurs when a local variable is referenced before it is assigned a value within a function 1 . This can happen if the variable is defined both inside and outside the function, and the function tries to modify the value of the variable defined outside the function. Here's an example of how this error can occur:

Here's an example of how this error can occur:

In [1]:

a = 1

def test():
    print(a)
    a = 2

test()

---------------------------------------------------------------------------
UnboundLocalError                         Traceback (most recent call last)
/tmp/ipykernel_2601534/2950199338.py in <module>
      5     a = 2
      6 
----> 7 test()

/tmp/ipykernel_2601534/2950199338.py in test()
      2 
      3 def test():
----> 4     print(a)
      5     a = 2
      6 

UnboundLocalError: local variable 'a' referenced before assignment

In this example, the variable a is defined outside the function test(). The function tries to print the value of a before assigning a new value to it. However, since a is also defined inside the function, Python treats it as a local variable and raises an UnboundLocalError when trying to access it before it is assigned a value.

To fix this error, the variable a can be declared as a global variable inside the function using the global keyword, or the function can return the modified value of a and assign it to the variable outside the function 1 . Here's an example of how to fix the error using the global keyword:

In [2]:

a = 1

def test():
    global a
    print(a)
    a = 2

test()
print(a)

1
2

In this example, the global keyword is used to declare a as a global variable inside the function. This allows the function to modify the value of a defined outside the function. The function first prints the value of a and then assigns a new value to it. The modified value of a is then printed outside the function.

"cannot access local variable 'a' where it is not associated with a value", but the value is defined

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