Adventures in Machine Learning

Avoiding Common Errors and Debugging Techniques in Python

Common Errors in String Operations

String operations are a crucial part of any programming language. We use strings to store text data and manipulate it as per our requirements.

In python, string data type is a sequence of characters enclosed in quotation marks. Strings are non-mutable, which implies any operation performed on strings return a new string, leaving the original one untouched.

However, while attempting to operate on strings or trying to manipulate them, programmers tend to make a few common mistakes. This article is aimed at educating you about these common mistakes and how to avoid them.

Handling the ‘str’ object has no attribute ‘append’ error

One of the most common mistakes while working with strings is calling append() method on a string object. The append() method belongs to the list datatype and can be used only with it.

When we call the append() method on a string object, Python will throw an AttributeError, stating that the str object has no attribute named append. For instance, consider the following code snippet:


name = “John”



The above code will throw an AttributeError as we cannot call the append() method on a string object.

Here, we were trying to append the last name to the first name. To achieve this, we should concatenate two strings using the + operator as shown below.


name = “John” + “Doe”


Alternatively, we can make use of formatted string literals to concatenate two strings as shown below:


fname = “John”

lname = “Doe”

name = f”{fname} {lname}”


Using the addition operator for string concatenation

Another common mistake while working with strings in python is using the + operator for string concatenation repeatedly. When we use the + operator to concatenate strings in a loop, Python creates new memory space for each concatenation.

This can be an issue when we are dealing with a large number of strings, as it may cause a memory error.

Consider the code snippet:


str1 = ”

for i in range(10):

str1 = str1 + ‘a’


The above code will concatenate ‘a’ to str1 using the + operator ten times, resulting in ten new memory locations.

To avoid this issue, we can make use of formatted string literals to concatenate strings. Formatted string literals use curly braces {} to encapsulate variables or expressions.

Consider the following code snippet:


str2 = ”

for i in range(10):

str2 = f'{str2}a’


Here, we are concatenating str2 with ‘a’ ten times using formatted string literals, instead of the + operator. It is a more efficient method when it comes to concatenating a large number of strings.


In conclusion, we have learned about two common mistakes that programmers make while working with strings in Python. The error that python throws ‘str’ object has no attribute ‘append’ occurs when we try to call the append() method on a string object.

To avoid this, we should instead concatenate strings using the + operator or make use of formatted string literals. Additionally, using the + operator repeatedly leads to a memory error, so it’s always preferable to use formatted string literals when dealing with a large amount of strings.

By avoiding these common mistakes, we can write efficient and optimized python code. Remember to always double-check the syntax and usage of methods while operating on strings, to avoid runtime errors.

Troubleshooting and Debugging in Python

Coding is a process that requires attention to detail and precision. As Python programmers, it’s essential to be able to identify potential errors and resolve them efficiently.

In this article, we will explore two effective methods to troubleshoot and debug code in Python.

Troubleshooting the error by identifying where the variable was assigned a string

One common error encountered while programming in Python is where a variable is assigned a string where a list was expected. This can occur due to a lack of careful attention to data types, or mistakenly assuming the variable’s data type.

Sometimes, we may assign a string to a variable instead of a list, leading to TypeError.

To solve this issue, we must identify where the variable was assigned a string instead of a list.

This can be done using the str.split() method. str.split() is a method that splits a string into a list at every occurrence of the specified delimiter.

If we apply str.split() to a variable that was assigned a string, Python converts it into a List type. Consider the following code snippet:


my_list = “1,2,3,4,5”

print(my_list[1]) # expected output: 2


In the above example, we have assigned a string to the variable `my_list`.

Accessing the second item of the `my_list` variable would result in a TypeError, stating that string indices should be integers. To resolve the issue, we can use the `str.split()` method to convert the string into a list.


my_list = “1,2,3,4,5”

new_list = my_list.split(“,”)

print(new_list[1]) # expected output: 2


In the revised code, we have used the `split()` method to convert the `my_list` string variable into the `new_list` list variable using the comma delimiter.

Debugging code with the dir() function

Another useful method to debug code in Python is by using the `dir()` function. `dir()` is a built-in Python function that returns a list of defined attributes and methods on an object.

This can be helpful when we’re not sure what methods or attributes are available to use with a specific object. Consider the following example:


my_list = [1,2,3,4,5]



In the above example, we are trying to append an integer value to a list using the `append()` method.

However, we have misspelled the `append()` method. Here, if we run the code, we will get the following error: “AttributeError: ‘list’ object has no attribute ‘appen'”.

To solve the issue, we can use the `dir()` function to identify the available attributes and methods of the `my_list` object. “`

my_list = [1,2,3,4,5]



The above code will output a list of available attributes and methods of the `my_list` object. By reviewing the output, we can identify that there is a method named `append()`.

We can now correct the typo in our code and run the program to append the integer value to the list correctly.


In conclusion, troubleshooting and debugging are essential skills required for any Python programmer. We must develop the habit of double-checking data types of variables to avoid assigning the wrong data type, leading to runtime errors.

The `str.split()` method can be used to convert a string to a list to avoid these issues. Additionally, using the `dir()` function can be helpful in identifying the attributes and methods available to use with a particular object.

By incorporating these methods into our debugging process, we can write efficient and optimized Python code.

Additional Resources for Error Handling and Debugging in Python

As a Python programmer, error handling and debugging are inevitable. Issues related to runtime errors, syntax errors, or logical errors require programmers to troubleshoot and debug code regularly.

With the availability of numerous resources, resolving errors can be made easier. In this article, we will explore some additional resources that can help with error handling and debugging in Python.

1. Python Documentation

Python documentation is an official resource to learn about Python.

Python documentation provides detailed information on the language structure, built-in functions, modules, and other objects in Python. When it comes to troubleshooting, the documentation can be used to identify the right methods, keywords, and parameters to use when a specific error occurs.

Python documentation is available online in various formats such as pdf, html, epub, and others. Developers can go through the documentation to get a better understanding of how Python works and how it can be used effectively.

2. Stack Overflow

Stack Overflow is one of the best community platforms for programmers to help each other.

Developers can ask questions related to any programming language, including Python, on this platform. Stack Overflow is relatively easy to use and provides a wide range of information on numerous programming topics.

When it comes to troubleshooting in Python, Stack Overflow can be incredibly helpful. If a developer has a specific error that isn’t well documented or requires personalized input from other developers, they can post the error on Stack Overflow.

Other developers may provide useful suggestions and solutions to the problem in question. 3.


A debugger is an interactive tool used to identify errors in the Python code. Debuggers can intercept the code at a specific location in the program and provide step-by-step execution of code, allowing developers to analyze the code for errors.

Python comes with a built-in debugger called Pdb, which is a command-line debugger. Pdb can pause the execution of the code and let developers proceed with the execution of the code line by line.

It provides numerous features, making it an excellent tool for debugging. 4.

IDEs and text editors

IDEs and text editors are essential tools for any programmer. Integrated Development Environment (IDE) and plain text editors come with useful features, making Python debugging and error handling more manageable.

Some of the commonly used IDEs and text editors for Python include:

* PyCharm

* Spyder

* VS Code

* Sublime Text

* Atom

IDEs and text editors provide useful features such as debugging tools, syntax highlighting, code formatting, and many more. Developers can pick the IDE or text editor that aligns with their style and requirements.

5. Online courses and tutorials

Numerous online courses and tutorials are available that teach Python with a focus on error handling and debugging.

These courses are designed to help developers learn how to handle errors and debug code like professionals. Some of the most popular online learning platforms for Python include:

* Udemy

* Coursera

* edX

* Codecademy

* Pluralsight

Online courses and tutorials provide a structured approach to solving errors, debugging code, and learning Python.

It allows developers to learn at their own pace and reinforce their Python knowledge.


In conclusion, error handling and debugging are an essential part of Python programming. With the various resources mentioned in this article, developers can improve their skills and get better at troubleshooting issues.

Python documentation, Stack Overflow, debuggers, IDEs and text editors, and online courses and tutorials provide a comprehensive range of resources for developers to improve their Python knowledge. With the right approach and resources, developers can minimize the errors, debug codes efficiently, and write optimized Python code.

In conclusion, error handling and debugging are essential skills for any Python programmer. Avoiding common errors, identifying the source of the error, and using the right tools can help developers save time, improve their code quality, and write optimized Python code.

Efficient use of resources such as Python documentation, Stack Overflow, debugger, IDEs and text editors, and online courses and tutorials can significantly enhance error-handling and debugging skills in Python. By mastering these skills, Python developers can develop robust, efficient, and optimized code, leading to the development of better software applications and solutions.

Popular Posts