Error Handling in Python: Printing Comparison Results with an EOL While Scanning Literal Error

In this article, we will explore the common error EOL while scanning literal in Python and how it relates to printing comparison results. We will also delve into the world of string formatting and provide examples to illustrate best practices for handling errors.

Understanding the EOL While Scanning Literal Error

The EOL while scanning literal error occurs when Python’s lexer encounters an invalid character or sequence at the end of a line. This can happen due to various reasons, such as:

• Incorrectly formatted strings
• Unhandled edge cases in code
• Syntax errors

In the context of printing comparison results, this error might manifest when attempting to concatenate strings with integer values using the + operator.

The Original Code: Identifying the Issue

The provided code snippet is as follows:

prod = df_merge[df_merge["_merge"]=="left_only"]
len(prod)
prod 1= df_merge[df_merge["_merge"]=="right_only"]
len(prod1)
prod_results = ("""compares two tables, records in prod only are""" "+str(len(prod)+"  """and records in prod1 are:  "  +str(len(prod)+" ")

The problematic line is prod_results = ("""compares two tables, records in prod only are""" "+str(len(prod)+"" """and records in prod1 are: " +str(len(prod)+")).

The Problematic Line

The issue with this line of code lies in the fact that it tries to concatenate a string literal (+) with an integer value using the + operator. This is incorrect because Python treats the + symbol as a special character, not a regular string concatenation operator.

When trying to print the results using print(prod_results), Python’s lexer encounters the invalid character and throws the EOL while scanning literal error.

The Corrected Code

To fix this issue, we need to use a more reliable way of formatting strings in Python. One such method is string formatting using curly brackets ({}).

Here’s how you can modify the original code:

prod = df_merge[df_merge["_merge"]=="left_only"]
len(prod)
prod1 = df_merge[df_merge["_merge"]=="right_only"]
len(prod1)

# Using f-strings for string formatting
prod_results = f"compares two tables, records in prod only are {len(prod)} and records in prod1 are: {len(prod1)}"

In the corrected code:

• We assign len(prod) and len(prod1) to variables (len(prod)) to avoid trying to concatenate strings with integers directly.
• We use an f-string to format the string. The {} placeholders are replaced with the values of len(prod) and len(prod1) using Python’s string formatting syntax.

Using String Concatenation

Another approach to fixing the issue is by using Python’s built-in str.format() method for string concatenation:

prod = df_merge[df_merge["_merge"]=="left_only"]
len(prod)
prod1 = df_merge[df_merge["_merge"]=="right_only"]
len(prod1)

# Using str.format() for string formatting
prod_results = "compares two tables, records in prod only are {}".format(len(prod)) + " and records in prod1 are: {}".format(len(prod1))

In this example:

• We use the str.format() method to replace placeholders ({}) with the actual values of len(prod) and len(prod1).

Conclusion

The EOL while scanning literal error in Python can be a confusing issue, especially when trying to print comparison results. By using f-strings or string concatenation methods like str.format(), we can avoid this error and ensure our code is correct and readable.

In conclusion, it’s essential to understand the basics of Python’s string formatting and to choose the most suitable method for your specific use case. Whether you prefer the concise and expressive syntax of f-strings or the flexibility of str.format(), these techniques will help you write more efficient and effective code.

Last modified on 2023-10-23