A function is the first class object that can be passed using arguments. While dealing with functions, TypeError: ‘function’ object is not subscriptable error is common. There can be many possible reasons for the error. In this short article, we will discuss the reasons for getting the error and will go through possible solutions as well. Moreover, we will also cover how we can interpret and understand errors in Python taking TypeError: ‘function’ object is not subscriptable as an example.
TypeError: ‘function’ object is not subscriptable – Possible Solutions
There can be many possible reasons for getting this error. One of the reasons is when we attempt to call a function with incorrect arguments. Another reason for getting the error is when trying to access the dictionary or list with the wrong syntax.
Let us take some examples and see when and how we are getting this error.
As we discussed one reason for getting TypeError: ‘function’ object is not subscriptable error is when we call a function with an incorrect of arguments. For example, see the following script below:
# a function def main(msg): print(msg) # calling the function msg = "Hello world!" # trying to access the function main
--------------------------------------------------------------------------- TypeError Traceback (most recent call last) /tmp/ipykernel_162703/280179824.py in <module> 7 8 # trying to access the function ----> 9 main TypeError: 'function' object is not subscriptable
The reason this error occurs is that when you try to call a function without any arguments but try to access it using the square brackets.
Now, let us try to solve the issue using various methods:
Solution-1: Calling a function using the correct syntax
We discussed that the error occurs when we used the square brackets to call and function. So, using the correct syntax to call a function will help us to get rid of the error. When you are calling a function, make sure that you are using the round brackets, not the square brackets.
The following is the correct way of calling a function:
# a function def main(msg): print(msg) # calling the function msg = "Hello world!" # trying to access the function main(msg)
Notice that we used the round brackets to call a function which helps us to solve the TypeError: ‘function’ object is not subscriptable error.
Solution-1: Passing a list to the function
Sometimes, you might be confused about how to pass a list to the function because a list has square brackets. We can still pass a list to the function but you should keep the list inside the round brackets when calling a function.
See the simple example below:
# a function def main(msg): print(msg) # trying to access the function main(['Hello', 'world'])
As you can see, the function takes a list and then prints the second element of the list. We have passed the list as an argument to the list which is inside the round brackets.
Solution-3: Having the same variable names
Sometimes, you might get the error because you have defined the name of the variable same as the name of the function. For example, let us say we have a list named main and then a function with the same name:
When we try to access the elements of the list using a square bracket, we will get TypeError: ‘function’ object is not subscriptable because of the same name as the function.
# a list main = [1,2,3,4,5,6] # a function def main(msg): print(msg) # trying to access the list main
--------------------------------------------------------------------------- TypeError Traceback (most recent call last) /tmp/ipykernel_162703/3259906954.py in <module> 7 8 # trying to access the list ----> 9 main TypeError: 'function' object is not subscriptable
The reason for getting this error is that first, we created a variable names main. Then we defined a function with the same name and when we try to access the list, the name conflicted with the function, and the Python compiler thinks we are calling the function.
The simplest way to solve the error is if it is because of the conflict between the names, then you can change the name of the function with any other name.
Solution-4: concatenating data frames
Sometimes, you get the error because you try to concatenate multiple data frames using the round bracket. The following is the incorrect way to concatenate data frames.
joined_df = pd.concat(df1, df2)
This will raise TypeError: ‘function’ object is not subscriptable because we cannot directly provide the data frames to the
concat() function. We need to provide the data frames in the form of the list as shown below:
joined_df = pd.concat([df1, df2])
Notice that we have passed the data frames in the form of a list.
Understanding the TypeError: ‘function’ object is not subscriptable error
In Python, the errors have two main parts. The first part of the error represents the category of the error which in this case is the TypeError. The type error occurs when we try to perform an operation on a wrong data type or a data type that does not support such an operation.
The second part of the error gives more specific information about the error and helps us to figure out what kind of TypeError is there. In this case, it clearly says that a function object is not subscribable which means we are trying to access the function using the wrong operation.
What is Subscriptable in Python?
Subscriptable in Python means the object implements the getitem() method. In other words, the object contains more sub-objects. It is used for objects that are like a container and contains other objects. Subsriptable objects in Python include strings, lists, tuples, and dictionaries.
The following are some of the built-ins that are subscriptable in Python:
What is a Function in Python?
A function in Python is a block of codes that is only executed when it is called. In Python, we use round brackets to call a function. The def keyword is used to define a function.
Let us create a simple function using the def keyword:
# a function def main(msg): print(msg)
As you can see, we have a function that has a parameter. This code will not be executed unless we explicitly call the function.
Let us now call the function in order to execute the code inside the function.
main("This is message")
We are now calling the function by providing one argument. The function prints the message as an output.
In this short article, we discussed how we could solve TypeError: ‘function’ object is not subscriptable error using various methods. Moreover, we covered various possible reasons for getting the error as well. The error mostly occurs when we try to call a function using the wrong brackets or forget to put the data frames inside the list when performing the concatenating method.
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