Unit 6: Lists and Loops Concepts

Unit 6: Lists, Loops, and Traversals

• Lists are ordered collections of elements, each assigned a unique index.
• Elements in a list are referenced using indices (numerical positions within the list).
• Iteration is a repetitive portion of an algorithm, often repeating a specified number of times or until a particular condition is met.
• An infinite loop occurs when the ending condition never evaluates to true.
• Data abstraction simplifies complex programs by giving data names without describing the representation in detail.
• Key list operations include:
  • appendItem(list, value): Adds a value to the end of the list.
  • removeItem(list, index): Removes the element at the specified index.
  • insertItem(list, index, value): Inserts a value at a specific position within the list.
• List length can be found using list.length.
• For loops iterate a specific number of times, typically with a syntax like for (var i = 0; i < list.length; i++) to iterate over each element in the list.

Loops

• For loops repeat a specific number of times.
• for loop syntax structure: for (var i = 0; i < list.length; i++)

While Loops

• While loops repeat until a condition becomes false.
• Avoid infinite loops by making sure the condition evaluates to false eventually..

Traversals

• Traversals access each element in a list one by one.
• Filtering elements involves applying conditions to decide whether to include or exclude elements.

Boolean Conditions

• if (condition): Checks if a condition is true.
• Conditions in loops need to eventually evaluate to false to prevent infinite loops.

Simulations

• Simulations model real-world scenarios using loops and conditions.
• Example: Coin flip simulation (predicting the outcome of multiple coin tosses)
• Simulate outcomes of events, using loops for each iteration to simulate.

Debugging Tips

• Ensure loops have proper stopping conditions.
• Check list indices to avoid going out of bounds.
• Use print statements (e.g., console.log()) to track variable values during debugging.

Example Questions and Answers

• Question: What does the program var list = ["tree", "rock", "air"]; list[0] = list[2]; console.log(list); output?
  • Answer: ["air", "rock", "air"]
• Question: What is the minimum value in the list [15, 20, 22, 23, 1]?
  • Answer: 1

Grid-Based Traversal

• Grid coordinates are like 2D arrays, (row, column).
• Robot movement commands include moveForward(), turnLeft(), turnRight().
• Loops and conditions can control robot movement to complete tasks like reaching a specific location on a grid.