Python Programming Fundamentals Quiz

Conditional Execution in Python

• Control flow determines the order in which statements in a program are executed.

• Python code typically has sequential control flow, but different control structures can result in different types of control flow.

• The most basic control structure is a sequence of statements executed in order of appearance.

• In a selection control structure, a condition determines which statements are executed, introducing multiple paths for control flow to take.

• Drawing the control flow over a flowchart can be helpful in reasoning about a program's logic.

• Python has three main selection statements: if, elif, and else.

• Simple conditional execution using if statements executes a block of code if a condition is truthy, and skips it if falsy.

• Alternative execution using if-else statements executes one block of code if the condition is truthy, and another block if falsy.

• Chained conditionals using if-elif-else statements introduce the possibility of many different branches in the same selection control structure.

• Common pitfalls when dealing with conditional execution include incorrect indentation, empty blocks, and missing variable definitions.

• Nested if statements can be used for complex decisions, but can get confusing. Tracing control flow with print statements can help to debug issues.

• The next lecture will cover the iteration control structure for executing the same code multiple times.Iteration Control Structures: While Loops and Nested Loops

• By the end of week 4, learners should be able to use iteration control structures, Python range, and perform aggregations.

• While loops are used when a program requires the same action to be performed multiple times, but the data might change.

• Definite loops repeat a fixed number of times, while indefinite loops repeat for a number of times that is not obvious before starting the loop.

• Interactive loops finish based on user input, and computed loops finish based on a complex computation made by the loop.

• An infinite loop never finishes and occurs when the condition is always truthy.

• Nested loops multiply the number of times that the innermost loop is repeated.

• A continue statement can be used to finish the current iteration early, while a break statement can be used to finish the entire loop early.

• A program can be written to print the times table for a number input by the user using while loops.

• Redundant code causes problems, such as being time-consuming to write, error-prone, and inflexible.

• The improved times table example uses a definite loop that loops 12 times.

• The total stopping time for the Collatz conjecture can be calculated using a computed loop.

• The for loop is another kind of loop in Python that will be covered in the next lecture.Python Iteration and Aggregation

• Python provides while and for loops for performing iteration.

• While loops are controlled by a condition, while for loops are a more convenient way of iterating over a sequence.

• For loops iterate over a sequence by assigning the next item to an iteration variable and executing statements in the for block.

• For loops share similarities with while loops, including the use of continue and break statements and following the same indentation rules.

• The range() function is commonly used in for loops to define the sequence to iterate over.

• To write a range sequence, one must ensure that all numbers are unique integers and that the sequence is an arithmetic sequence.

• Valid range sequences include incrementing and decrementing integers, while invalid sequences include non-unique integers and non-arithmetic sequences.

• The pattern for aggregation involves defining summary variables, writing a for loop to update the variables, and using the variables to calculate a final result.

• Common aggregation functions include sum, average, maximum, and count.

• Custom aggregation functions can be created by defining the sequence, summary variable(s), repeated operation(s), and final result.

• An example of custom aggregation is concatenating all single-digit numbers into one long string surrounded by square brackets.

• It is important to consider the order of conditions in selection structures when performing aggregation.Python Programming: Input, Output, Comparisons, and Boolean Logic

• Python programming involves a set of written actions to solve a problem using a programming language.

• Flowcharts, program development steps, input, processing, and output, variables, statements, and comments, expressions, and data types are the fundamentals of Python programming.

• Python allows input from users through direct or keyboard input, files, or systems.

• Input from users through the keyboard is achieved using the input() function, which takes a prompt message for the input.

• Values obtained from user input are saved as strings and can be converted to proper data types using explicit type conversion functions such as int(), float(), and str().

• Python can display output to the standard output device, such as the screen or console, and save output in files such as text, csv, binary, etc.

• Boolean data type is a binary value that represents yes/no, true/false, on/off values and is used to represent answers to yes/no questions.

• Python has two boolean literals, True and False, and values of other types can be converted to booleans, with truthy values representing True and falsy values representing False.

• Comparison operators such as ==, !=, >, <, >=, and <= are used to compare values, with the result being True or False depending on whether the condition is satisfied.

• Logical operators such as and, or, and not are used to modify boolean expressions and combine them to form more complex expressions.

• Python follows an operator precedence order in evaluating expressions, with parentheses having the highest precedence and logical or having the lowest.

• In the next lecture, boolean expressions will be used to control the flow of program execution.