INF1-IP: Week 3

Iteration

The act of repeating a process.

Loop

A control flow structure that repeats code according to a particular condition

Iterable

An object that can be iterated over, such as a list, string, or range().

Accumulator

A variable whose value is gradually constructed over the course of multiple iterations of a loop.

Nesting

Putting multiple control flow structures inside of one another.

Infinite loop

A loop that never ends, often completely consuming or even crashing the program that runs it.

while

A loop that repeats its body while the condition in its header is true (unless its body exits early with break).

for

A loop that runs its body once for each item supplied by an iterable.

in

A keyword used in the head of a for loop to iterate through a sequence.

range(start, stop, step)

A function that generates integers from start up to but not including stop, taking step steps at a time. When not provided, start defaults to 0 and step to 1.

break

A keyword that immediately exits the nearest enclosing loop.

continue

A keyword used to skip the rest of the current iteration of a loop and begin the next one.

pass

A keyword that does nothing and can be used as a placeholder for an unfinished body. It does not skip an iteration; that's continue!

List

A data structure (list) that keeps data in order using integer indices.

Set

A data structure (set) that keeps data unordered and deduplicated.

Dictionary

A data structure (dict) that keeps data in an ordered collection of key-value pairs.

Index

A unique value that points to an item in a collection. In a list, this is an integer; in a dictionary, this is the key.

Key

A value used to look up an entry in a dictionary. Can be a string or a number.

Immutable type

A type whose objects cannot be changed after creation. Includes str, int, float, and bool.

Mutable type

A type whose objects can be changed after creation. Includes list, set, and dict. Multiple names can refer to the same mutable object, so changes may be visible through all of them.

Shallow copy

A copy of a collection, created using .copy(), that only creates a copy of the top-level collection, leaving any nested collections to point to their original locations in memory.

[a, b, c]

A list containing the items a, b, and c; indexed by the integers 0, 1, and 2.

{a, b, c}

A set containing the items a, b, and c. Adding an item already present leaves the set unchanged.

{a: 1, b: 2, c: 3}

A dictionary containing the keys a, b, and c, mapping on to the values 1, 2, and 3, respectively.

list()

A function that (when empty) creates a new list or (when passed a set) converts a set to a list.

set()

A function that (when empty) creates a new set or (when passed a list) converts a list to a set.

list[index], dict[key], and string[index]

Accessing a list item by its index, a dictionary value by its key, and a string character by its index. Remember, indices in Python start at 0!

len()

Returns the length of a string, list, set, or dictionary.

in (when used outwith for loops)

Membership operator that checks whether an item is present in a list, set, or dictionary.

KeyError

A type of error that highlights when you're trying to access a non-existing key in a dictionary

List methods

list.append(item)

Add item to the end of list.

list.insert(index, item)

Add item to list at position index.

list.extend(list_2)

Adds the items from list_2 individually to the end of list.

list.pop(index)

Remove the item at position index from list. If not provided index, removes the last item in the list.

list.remove(item)

Removes the first occurrence of item from list.

list.copy()

Creates a shallow copy of list.

Dictionary methods

dict.values()

Provides a view of the values in dict for iteration. It does not create a list.

dict.update({key: value})

Adds or updates each key-value pair from the supplied dictionary. Any new keys are added and existing keys receive the new values.

dict.pop(key)

Remove the key-value pair at key from dict.

dict.copy()

Creates a shallow copy of dict.

Set methods

set.add(item)

Adds item to set if it is not already present.

set.copy()

Creates a shallow copy of set.

Symbolic AI

An approach to AI that represents information explicitly using symbols and rules for manipulating them.

ELIZA

Joseph Weizenbaum's early chatbot, described in 1966. Its DOCTOR script used patterns and response rules to imitate aspects of a psychotherapist's conversation.

Tokenisation

Breaking text into smaller pieces, called tokens, for a program to process. EDIZA uses words as tokens; other systems may use smaller pieces.

Barnum effect

Treating a broad personal description as if it were specifically accurate about you.

ELIZA effect

Attributing understanding to a computer because of the responses it gives.