AP Computer Science Principles

BIG IDEA 1

Creative Development, which is 13% of the exam.

Computing innovation

Uses a computer program to take in data, transform data, and output data.

Collaboration

Occurs in the planning, testing, or designing step of the process.

Benefits of collaboration

Includes the ability to exchange ideas, multiple perspectives, addressing misunderstandings, development of thinking skills, increased student responsibility, and elimination of bias.

Pair programming

When two programmers develop software side-by-side at one computer on the same algorithm.

User interface

The inputs and outputs that allow a user to interact with a piece of software.

Camel case

A naming convention where the first letter of each word is capitalized, e.g., stopButton.

Input

Data that is sent to a computer for processing.

Output

Data sent from a program to a device.

Program

A collection of instructions that a computing device executes.

Code segments

Smaller collections of statements that are part of a program.

Program event

An action or occurrence within a computer program that triggers specific actions or behaviors.

Event driven program

A type of program that responds to events triggered by user actions, system events, or other sources.

Sequential program

A program that executes instructions in a specific order.

Iterative development process

Programmers develop working prototypes and revisit stages of their development method.

Incremental development process

Programmers break the program into smaller pieces and ensure each piece works before adding it to the whole.

Program Documentation

A description of how something in your program works.

Comments

The most common form of program documentation, written directly into the program.

Library

A collection of functions that can be used in different programs.

Application Program Interface (API)

Describes how each function works, a complete list of parameters, and what is returned.

Syntax Errors

Occurs when the spelling and/or punctuation rules of the programming language aren't followed.

Syntax Error

An error caused by incorrect syntax, such as forgetting to close a set of parentheses or spelling a variable wrong.

Logic Errors

A mistake in a program's base logic that causes unexpected behavior.

Run-Time Errors

An error that occurs when the program is running, allowing the program to start but causing issues during use.

Overflow Errors

An error that occurs when a computer tries to handle a number that's outside of its defined range of values.

Debugging

The process of finding and fixing errors in a program.

Data

A collection of facts.

Number Base

The number of digits or digit combinations that a system uses to represent values.

Decimal System

A system with a base of 10 that uses combinations of 0-9 to represent values.

Binary System

A system that only uses combinations of 0 and 1 to represent values.

Bits

The smallest unit of information stored or manipulated on a computer, represented as 0 or 1.

Byte

A unit of data that consists of 8 bits.

Analog Data

Data that is measured continuously and changes smoothly.

Digital Data

Data that is formatted in a finite set of possible values.

Sampling

The process of recording an analog signal at regular discrete moments and converting them into digital signals.

Data Abstraction

Filtering out specific details to focus on the information needed to process the data.

Unique Combinations of 8 Bits

8 bits can represent 256 unique combinations.

Representation of Number 5 in Binary

The binary representation of the number 5 is 101.

Representation of Number 5729 in Decimal

The decimal representation of the number is 5,729.

Black and White in Binary

Black is represented as 1 and white as 0.

Digital Representation of Analog Data

Digital data approximates real-world analog data by leaving out extra details.

Example of Digital Data

Watching a video on YouTube, where the duration is displayed in finite values.

Example of Analog Data

Observing a live game at a venue, where the data is continuous.

Largest value calculation

To Calculate the largest value: do the power of 2 -1. For example, what's the largest value you can represent with 7 bits: 2 to the 8th -1 which is 255.

Largest numerical values calculation

To calculate the largest amount of numerical values you just do the power like 2 to the 8th which is 256. That's because we count 0-255.

Data compression

Set of steps of packing data into a smaller space while allowing for the original data to be seen.

Two way process of data compression

Make a data package smaller or decompress packet to original form.

Purpose of data compression

Useful in computing to save disk space or to reduce bandwidth.

Data compression process

Deals with a string of bytes and compressing it down to a smaller set of bytes, taking less bandwidth.

Condensing large files

Condense large files by getting rid of data that isn't needed while retaining the information in the file.

Redundancy in data compression

Contain large amounts of redundancy to get a compact representation of the data.

Encoding algorithm

An encoding algorithm that takes a message or image and generates a compressed representation.

Decoding algorithm

A decoding algorithm that reconstructs the original message or an approximation of it.

Factors affecting data compression

Depends on the amount of redundancy or repeated information and the method you use to compress your file.

Run length encoding

Works by replacing repeating data with a run that represents the number and value of the repeated data.

Example of run length encoding

For example, FFFFFIIIIIIVVVVVVVEEEE could be written as 5F6I7V4E.

Lossless data compression

Allows you to reduce your file size without sacrificing any of the original data in the process.

Inverting pixel colors

Inverting pixel colors and brightness values can reconstruct the original message exactly from the compressed message.

Lossy data compression

Sacrifices some data in order to achieve greater compression.

Methods of lossy compression

Converting to grayscale, lowering resolution.

Reconstruction in lossy compression

Can only reconstruct an approximation of the original message.

Usage of lossy compression

Used mainly for images and sound.

Effects of lossy compression

High degrees of compression result in smaller compressed files but some number of original pixels, sound waves, or frames are removed FOREVER.

Compression and file size

Amount of compression ⬆️ Size of resulting file ⬇️.

Information extraction from data

Large data sets: big data.

Correlation definition

Correlation DOES NOT CAUSE: Correlations refer to the statistical relationship between two or more variables.

Correlation range

It measures how closely these variables are related to each other, ranging from -1 (perfect negative correlation) to 1 (perfect positive correlation).

Outliers in data

Data points that significantly deviate from the overall pattern or trend.

Metadata definition

Metadata is data about data. IT DOES NOT AFFECT THE DATA ITSELF!! Changes and deletions made to metadata do not change the primary data.

Purpose of metadata

IT IS USED TO help find and organize data.

Data cleaning

Data may not be uniform so you have to clean data. Cleaning data creates a uniform of data.

Data cleaning

The need to clean data.

Incomplete data

Data that is missing some values.

Invalid data

Data that is incorrect or not usable.

Combining data sources

The need to combine data from different sources.

Parallel systems

Systems that may be required to process large data sets using multiple computers.

Bias in data

Problems of bias created by the type or source of data being collected.

Data mining

The process of examining very large data sets to find useful information such as patterns.

Spreadsheets

Programs that help efficiently organize and find trends in information.

Data transformation

Modifying every element of a data set.

Arithmetic modification

An example of data transformation, such as multiplying each number by some constant value.

Non-arithmetic modification

Adding a grade level or class rank to a list of student records.

Filtering data

Filtering a data set by category, such as extracurricular activities.

Data visualization tools

Tools such as graphs, charts, and word-bubbles used to represent data.

Bar chart

A chart that presents categorical data with rectangular bars with heights or lengths proportional to the values they represent.

Scatter plots

Uses dots to represent values for two different numeric variables.

Correlation

A measure that indicates the relationship between two variables.

Causation

Indicates that one event is the result of the occurrence of another event.

Strong positive correlation

A correlation value close to 1.

Line graphs

Graphs that use lines to represent values.

Histogram

Uses bars to represent values, usually using frequency and ranges.

Grades range

Grades were about 60-80.

Variable

A placeholder in your program for a value, usually represented by letters or words.

Assignment operator

Used to assign values to variables.

Global variable

A variable that can be used anywhere in the code.

Local variable

A variable used only in part of the code it was created and deleted once the event is done.

Avoid local variables

Best practice to create variables once and place them on top of the code.

Data value

Each variable can only hold one data value at a time and can be reassigned.

Animal

The variable Animal is now 'dog'

Data types

Different categories of data that your computer can represent, such as integers, strings, lists, and booleans.