DSC 20 Discussion 2

Imports

Makes code from other packages available in your code.

Escape Character

• \ is the escape “operator”
• bypasses the next character for some functionality

Loops

loops are used to repeat computations many times
two types of loops:

• while loop: uses logical conditions
• for loop: uses an iterable object

List

• mutable vector of values
• can store any data type, multiple types at a time
• elements are accessed via indexing

Tuple

• immutable vector of values
• all else equal to list

Set

• mutable vector of values
• only stores unique elements (removes duplicates)
• otherwise, list like behavior

Mutability

• Object is mutable if it can be directly changed after it is created
• If it can’t, it is immutable
• Lists are mutable
• Strings, tuples, and numbers are immutable

Indexing/Slicing

indexing/slicing refers to accessing specific elemtn(s) from an iterable object

• iterablestart:stop:skip
• not every section needs to be specified (can just use start or stop or skip)
• sub indexes can be applied
• trying to access an index that doesn’t exist in the list will result in an error

In-Place Operations

An operation is in-place if the result occurs directly …

List Methods

• list.pop(index) removes the element at index. in-place operation. returns the value removed.
• list.append(element) adds the element to the end of the list. in-place operation
• list.sort() sorts the list. can specify ascending or descending

String Methods

• string.split(separator) splits a string into a list of elements on each separator
• [string].join(iterable) returns the iterable “joined” with the [string] in between each element
• string.lower()/string.upper() lowers/uppers all elements in a string
• string.title() changes to title case like a book
• string.strip() removes whitespace from beginning and end of the string

Dictionaries

• Mutable storage of key, value pairs
• Can store any data type, multiple at a time
• Elements are accessed via keys
• Keys must be hashable and unique
  Methods
• dict.keys() accessing keys
• dict.values() accessing as values
• dict.items() accessing key, value as pairs