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Python Functions

Use functions to help with repetitive tasks when working with your data.

Python Python Functions type error 

TypeError: the first argument must be callable

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Estimated reading time: 3 minutes

So you may be using Python Classes and have encountered the problem TypeError: First Argument Must be Callable. So what does the problem mean and how can you fix it?

In this article, we are looking to explain how it may occur and the easy fix you can apply to stop the problem in the future.

Let us understand calling Functions/Methods first

Normally in a computer python program, you will have a need to use a function/method as it has the functionality that will save you time, and can continuously be reused.

A classic example is print(“Hello”) that handles all the required logic to show this on a screen. Its output is quickly viewable, and there is not any need to understand what is going on in the background.

Here in this example we have run the function on its own, as a result it does not need to pointed to somehwhere else to run the logic it contains.

For the error we are looking to resolve, this is part of the problem. A function/method can be run on its own, or from within a Class.

The defining differene is that on its own it needs the parenthensis i.e. (), but if if you calling it from within a class, then it has to be handled differently.

Seeing the Type Error First Argument must be callable and fixing it

In the below we have a block of code, that produces the error we are trying to fix.

Following on from what was discussed above, the offending line is highlighted.

In particular the problem lies with printprogress() . This is been called , but in actual fact the problem is that when you have the logic written like this, it gives the error this blog post was setup for.

In essence it is trying to run the program from that exact point, which python does not allow.

Removing the parenthesis then allows the program to go and find the module it is referencing and then run the logic contained within that.

import schedule
import time

class scheduleprint():

    def printprogress(self):
        print("Start of Processing")
        print("Processing Complete")

    def schedule_a_print_job(self, type="Secs", interval=5):

        if type == "Secs": # Fed from the function paramaters
            schedule.every(interval).seconds.do(self.printprogress())===> The problem is here, remove the () after printprogress.
            # Including the parentheses  after printprogess will throw an error as you cant run that method directly from there you can only call it.

        if type == "Mins": # Fed from the function paramaters
            schedule.every(interval).minutes.do(self.printprogress)
            # Including the parentheses  after printprogess will throw an error as you cant run that method directly from there you can only call it.

        while True:
            schedule.run_pending()
            time.sleep(1) # The number of seconds the Python program should pause execution.

run = scheduleprint() # initiating an instance of the class "scheduleprint"
run.schedule_a_print_job() # running the function contained within the class.

In summary to help troubleshoot this problem:

(A) Check your code to see where it is calling a module within a class.

(B) Next make sure that in that call no parenthesis are present, otherwise it wont be able to find the module.

Python Functions type error 

TypeError: ‘str’ object is not callable

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Estimated reading time: 2 minutes

This is a common TypeError that you will come across in Python, it is actually easy to diagnose how it occurred.

To start off we need to understand “str” is a function in python, and it converts any value into a string.

As a result , because it is a function your ability to call it has limitations.

So in essence it has parenthesis () beside it, and allows parameters to be passed to it.

So lets first look at how the string function works:

x = str("10")
y = 10

print(type(x))
print(type(y))
print(x)
print(y)

With output:
<class 'str'>
<class 'int'>
10
10

As you will see the above the value 10, on its own is an integer, but when you call the string function, it now becomes a string.

For this reason this , calling a string function , completes a conversion to string of ten, but what if the variable is called str?

Lets take an example below from an input:

str = input("what year where you born?")
print(str(str))

Output:

what year where you born?2021
Traceback (most recent call last):
  File "str obj is not callable.py", line 2, in <module>
    print(str(str))
TypeError: 'str' object is not callable

Process finished with exit code 1

The reason for this error above , is that we have named the variable “str”.

As can be seen the programme is trying to use the first str in the print statement as a function.

As we know by now string variables are not callable.

Accordingly the function str() which the programme is trying to run, fails with the TypeError identified.

For this reason to fix this problem we would change the variable called str to “year”, the error then disappears.

The updated code will work as when calling str(), it is not conflicted with a variable name.

year = input("what year where you born?")
print(str(year))

Output:
"str obj is not callable.py"
what year where you born?2021
2021

Process finished with exit code 0

So to summarise:

  • Strings are not callable
  • Don’t name a variable as str, or any function name, these are reserved words by the system.
  • Functions are callable, strings are not.

Python Python Functions tkinter 

Tkinter GUI tutorial python – how to clean excel data

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Estimated reading time: 2 minutes

Tkinter is an application within Python that allows users to create GUI or graphical user interfaces to manage data in a more user-friendly way.

We are building our data analytics capability here, and looking to provide the user with the functionality they use in their work or college projects.

We have tested this code over 100,000 records sitting on the Microsoft OneDrive network so in a way, for this reason, its speeds were quite good.

As a result over five tests, they all were under 100s from start to finish.

data cleansing data cleansing fixed

In this Tkinter GUI tutorial python, you will be shown how to find the data errors, clean them and then export the final result to excel.

We will take you through the following:

  • Creation of the Tkinter interface.
  • Methods/ functions to find errors.
  • Methods/functions to clean the data.
  • Exporting the clean data to an excel file.

 

To sum up:

The video walks through the creation of a Tkinter window using a canvas and a frame to store the data frame.

Then it looks at importing the data through pd.read_excel, to load the data into a pandas data frame.

Next, there is a function and or method that will extract the errors through str.extract , which is loaded into separate columns

Finally, I have exported the clean dataset using rawdata.to_excel , and saved the file as a separate new spreadsheet.

Python Functions Python Tutorial 

how to pass data between functions

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Estimated reading time: 2 minutes

In this python program, we are learning how to pass data between functions. 

In light of this, you will use and see functions in many programming languages and data analytics projects.

As a result, the ability to understand them has become important.

Functions serve a number of benefits:

  • You can pass a number of arguments to them to be processed.
  • It reduces repetition as the function can be called from many places with a program.
  • They are easily identified by using the def keyword in your code.
  • A return statement can give you the output of the function to show on the screen or pass to another function.

It compliments r-tutorial-how-to-pass-data-between-functions/  as a result this is a handy bit of functionality used widely across many different programming languages.

Below is a video that will help to give an understanding of how to pass data between functions when trying to learn python:

 

In many of the Data Analytics Ireland    YouTube channel videos, there is an emphasis on creating content that eliminates duplication of code within the code.

We have also started incorporating classes as well and you can see here How to create a class in Python, a tutorial on how to create one.

Classes by their nature have methods, which are called on the objects that created them ( the class), and can alter their state, whereas a function will run and just return a value.

It is important to understand the distinction as while the two will most likely achieve the same outcome, it is the ability to change the class state that will differentiate the two.