Python Lists, Tuples, Dictionaries, Sets

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Questions and Answers

What does the `dir()` function do in Python?

Returns a list of the attributes and methods of any object.

Which methods are returned for a list when using `dir()`?

append, clear, copy, count, extend, index, insert, pop, remove, reverse, sort

Which methods are returned for a tuple when using `dir()`?

count, index

Which methods are returned for a dictionary when using `dir()`?

clear, copy, fromkeys, get, items, keys, pop, popitem, setdefault, update, values Signup and view all the answers

Which methods are returned for a set when using `dir()`?

clear, copy, fromkeys, get, items, keys, pop, popitem, setdefault, update, values Signup and view all the answers

What is the purpose of the `append()` method in Python?

To add an element to the end of a list. Signup and view all the answers

What does the `clear()` method do in Python?

Removes all elements from a list. Signup and view all the answers

What is the function of the `copy()` method in Python?

Creates a shallow copy of a list. Signup and view all the answers

How does the `count()` method work in Python?

Counts the occurrences of a specified element in a list. Signup and view all the answers

What does the `extend()` method do in Python?

Adds elements from one list to the end of another list. Signup and view all the answers

What is the purpose of the `index()` method in Python?

Finds the index of the first occurrence of a specified element in a list. Signup and view all the answers

Study Notes

dir() Function in Python

The dir() function lists attributes and methods of any object in Python3.
Syntax: dir({object}) where {object} is optional.
Helps in understanding available methods for data structures such as Lists, Tuples, Dictionaries, and Sets.

Methods for Lists

Created using l = [] or l = list().
Common methods:
- append(): Adds an element at the end.
- clear(): Removes all elements.
- copy(): Creates a shallow copy.
- count(): Counts occurrences of a value.
- extend(): Combines another list.
- index(): Finds the index of the first occurrence.
- insert(): Adds an element at a specified index.
- pop(): Removes an element at a specified index or the last element.
- remove(): Deletes the first occurrence of a value.
- reverse(): Reverses the list.
- sort(): Sorts the list.

Methods for Tuples

Created using t = () or t = tuple().
Common methods:
- count(): Counts occurrences of a value.
- index(): Finds the index of the first occurrence.

Methods for Dictionaries

Created using d = {} or d = dict().
Common methods:
- clear(): Removes all key-value pairs.
- copy(): Creates a shallow copy.
- fromkeys(): Creates a new dictionary from keys.
- get(): Retrieves a value for a given key.
- items(): Returns a view of key-value pairs.
- keys(): Returns a view of keys.
- pop(): Removes a specified key and returns its value.
- popitem(): Removes and returns the last key-value pair.
- setdefault(): Returns the value of a key, or sets it.
- update(): Updates dictionary with key-value pairs from another dictionary.
- values(): Returns a view of values.

Methods for Sets

Created using s = set().
Common methods:
- add(): Adds an element.
- clear(): Removes all elements.
- copy(): Creates a shallow copy.
- difference(): Returns elements not in another set.
- discard(): Removes an element without raising an error.
- intersection(): Returns common elements with another set.
- pop(): Removes and returns an arbitrary element.
- remove(): Removes a specified element.
- union(): Combines two sets.

Exercises Summary

Append: Program to continuously add integers to a list until 'done' is entered.
Clear: Program demonstrating the clear() method to empty a list.
Copy: Highlights how changes to the original list don't affect the copied list.
Count: Program that counts occurrences of a user-provided character in a list.
Extend: Combines two user-input integer lists into one using extend().
Index: Demonstrates finding the index of a string in a list, with error handling for a missing string.

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Description

This quiz focuses on the practical exercise of using the dir() function in Python 3 to explore the attributes and methods of Lists, Tuples, Dictionaries, and Sets. It provides an understanding of the syntax and parameters of the dir() function, aiding in object-oriented programming in Python.