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Conditionals | The Basics of Decision-Making

We will be talking about conditionals which are generally known as if and else in programming languages.

Welcome back, bioinformatics enthusiasts!

In this post, we’re diving into conditionals, one of the most fundamental concepts in programming. Conditionals allow your code to make decisions, and mastering them is key to writing flexible and intelligent scripts.

What Are Conditionals?

Conditionals in Python let you execute specific blocks of code based on whether certain conditions are true or false. There are three main types of conditionals in Python:

1. The if Statement

The if statement is the simplest type of conditional. It checks a condition, and if the condition is True, it executes the block of code inside it.

Syntax

if expression:
    # Statements to execute if the condition is True

Example: Basic Comparison

a = 10
b = 100

if a < b:
    print("a is less than b")

Output: a is less than b

Example: Validating a DNA Sequence

We can integrate conditionals with bioinformatics by using the validate_base_sequence function from the pyforbinf module.

from pyforbinf import validate_base_sequence

seq = "ATGC"

if validate_base_sequence(seq):
    print("This is a DNA sequence")

Output: This is a DNA sequence

2. The if-else Statement

The if-else statement provides an alternative action if the condition in the if statement is not met.

if expression:
    # Statements if the condition is True
else:
    # Statements if the condition is False

Example: Basic Comparison

a = 10000
b = 100

if a < b:
    print("a is less than b")
else:
    print("a is greater than b")

Output: a is greater than b

Example: Validating a Potential DNA Sequence

seq = "AXGC"

if validate_base_sequence(seq):
    print("This is a valid DNA sequence")
else:
    print("This is not a valid DNA sequence")

Output: This is not a valid DNA sequence

3. The if-elif-else Statement

The if-elif-else statement allows you to check multiple conditions in sequence. The first condition that evaluates to True gets executed.

if expression1:
    # Statements if expression1 is True
elif expression2:
    # Statements if expression2 is True
...
else:
    # Statements if none of the above conditions are True

Example: Comparing Values

a = 100
b = 100

if a < b:
    print("a is less than b")
elif a > b:
    print("a is greater than b")
else:
    print("a is equal to b")

Output: a is equal to b

Example: Identifying DNA and RNA Sequences

Here’s an example where we use if-elif-else to classify a sequence as DNA, RNA, or invalid:

seq = "AUGC"

if validate_base_sequence(seq):
    print("This is a valid DNA sequence")
elif validate_base_sequence(seq, True):
    print("This is a valid RNA sequence")
else:
    print("This is not a valid DNA nor RNA sequence")

Output: This is a valid RNA sequence

Key Takeaways

Combining conditionals with bioinformatics functions, such as sequence validation, allows us to solve domain-specific problems efficiently.

What’s Next?

Ready to learn more about control flow in Python? Join us in our next post, While Loops in Python, where we’ll explore how to repeat actions until a condition is met - a crucial concept for processing biological sequences and implementing iterative algorithms in bioinformatics.

If you have questions or want to share how you’re using conditionals in your bioinformatics projects, drop a comment below or join our bioinformatics community on Facebook. Don’t forget to check out my GitHub repository for all the code examples.

Happy coding! 🚀

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