Concepts

Key concepts introduced in this module.

Programming Foundations

Sequential Execution

Sequential execution runs instructions in order, once each, from top to bottom.

Python uses sequential execution. Useful programs often need more control than this: the ability to decide whether an instruction runs, and to repeat an instruction many times.

value = 10
double_value = value * 2
print(double_value)

Branching

Lets a program choose what to do based on a condition.

Python uses if, elif, and else. The condition evaluates to either True or False, and the program follows the matching branch. Analytical programs use branching to respond to different values and situations in the data.

if value > 0:
    print("positive")
else:
    print("zero or negative")

Boolean Expressions

A Boolean expression is a condition that evaluates to True or False.

It is what branching and repetition test against.

Comparison operators include:

value > 10
value == 0
name == "Adelie"

Repetition

Performs the same work more than once.

The work is described once, and Python repeats it. Each pass through the repeated block is one iteration.

For Loop

Repeats once for each item in a collection, and is a good choice when the collection is already known.

for value in values:
    print(value)

While Loop

Repeats as long as a condition stays True, and is a good choice when the number of repetitions is not known in advance.

while running:
    process_data()

List Comprehension (List to new List)

A list comprehension is a compact for loop that builds a new list by transforming an existing one with a simple transformation.

upper_names = [name.upper() for name in names]

Program Flow

State

State is the information a program remembers while it runs, held in variables that change as the work proceeds.

A repeating program might track how many items it has processed (a counter), a running total, the most recent values, or whether it should keep going.

Moving Average

Summarizes a limited window of recent values.

When a new value arrives, the oldest drops out and the newest joins. Moving summaries matter when recent observations count for more than the full history. For 8, 10, 12 the mean is (8 + 10 + 12) / 3 = 10.

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