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()
?
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Which methods are returned for a set when using dir()
?
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What is the purpose of the append()
method in Python?
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What does the clear()
method do in Python?
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What is the function of the copy()
method in Python?
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How does the count()
method work in Python?
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What does the extend()
method do in Python?
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What is the purpose of the index()
method in Python?
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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 = []
orl = 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 = ()
ort = tuple()
. - Common methods:
-
count()
: Counts occurrences of a value. -
index()
: Finds the index of the first occurrence.
-
Methods for Dictionaries
- Created using
d = {}
ord = 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.