Quick Tips

• Order is important because computer will run the codes/instruction in order

• White space (indentation) is important for how the program runs the functions

• Use the “+” sign to connect strings and values inside the print function, but both need to be the same data types; e.g. print(“Good afternoon, “ + name + “!”); if the data types are different, use a comma; e.g. print(“You are”, 12, “years old.”)

• You can have simultaneous assignment like so: L[0], L[1] = L[1], L[0]

Mutations

• Every object lives somewhere in memory, and the location of which can be determined using the id() function

• When an object is mutated, the contents change but the hex ID remains the same

• If a function mutates an object, there is usually no return; but exceptions include pop(), next(), readllines()

• When creating mutating functions, you do not want to include a ‘return’ statement because a different user may assume that the function is non-mutating

Useful Terminology

ASCII - American Standard Code for Information Interchange; character encoding standard that uses numbers from 0 to 127 to represent English characters

Byte - the basic unit of information in computer storage and processing

Bytestream - a sequence of bytes

Concatenation - appending (or attaching) another value but both data types must be of the same; e.g. if intro = “Hello! ” then print(intro + “How are you?) will output “Hello! How are you?”

Exception - errors detected during executions; refer to Try/Except

Expression - a piece of syntax which can be evaluated to some value; i.e. anything that returns a value like operators or function calls

Function - a block of reusable code that can be called upon and perform a single action; data that passes through the function (also known as parameters) can return data as a result in most cases

Hash Value - an assigned integer which is used to quickly look up sets or dictionaries (faster than going through a long list through “for x in list”)

Hex Code - short for hexadecimal; used in many areas of computing to simplify binary codes

Index - position, denoted in brackets [ ]; first position starts from zero; negative index starts from the end of the string and goes backward. E.g.; for the string ‘HELLO’, the letter ‘H’ has an index of [0] or [-5], ‘E’ is [1] or [-4], ‘L’ is [2] or [-3], ‘L’ is [3] or [-2], and ‘O’ is [4] or [-1]

Instance - an object that belongs to a class; e.g. when we create a list, we have an instance of the list class

Lambda - “anonymous function”; a function that can be defined without a name

Method - a function that belongs to an object or class, usually preceded by a period; e.g. list.append()

Parsing - the process of converting codes to machine language to analyze the correct syntax of the code

Program - a sequence of instructions that specifies how to perform a computation; the computation can be mathematical or symbolic/textual

Recursion - defining something in terms of itself to achieve your objective

Recursive function - a function that calls itself in its body

Semantic error - when program runs successfully without error messages but does not do the right thing

Statement - a block of code that is either an expression or one of several constructs with a keyword, such as ‘if’, ‘while’, or ‘for’

Syntax - the structure of a program and the rules about that structure

Variable - a name assigned to a value or object so it can be referred to or called on later

• this adds interpretability to the function; e.g. instead of running $299 * 1.1475 straight into the program, I can assign the variables rate = $299 and taxes = 1.1475 and create an interpretable function rate * taxes

• case sensitive and no spaces

• always start with a letter or underscore, but the rest can include letters, numbers, and underscores

• single-letter variables are usually frowned upon; but i, j, and k are often used for indexes

• avoid using reserved names because you will override them; alternatively, add an underscore or number at the end

• df is used for “dataframe”

Operators

Chained comparisons allow multiple operators in a single line; e.g. x<y<z vs. x<y and y<z

This is the order in which Python runs the operators in chained comparisons:

• ** (exponentiation)

• *, /, //, % (multiplication, division, modulus)

• +, - (addition, subtraction)

• & (Bitwise AND)

• ^ (Bitwise XOR)

• | (Bitwise OR)

• comparison, identity, and membership operators

• not (Boolean NOT)

• and (Boolean AND)

• or (Boolean OR)