Network Prog Ch 2: Python Data Types

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Questions and Answers

What is a list in Python?

A container that holds a fixed number of other objects.

A container that holds a number of other objects in a given order. (correct)

A type of immutable data structure.

A collection that can only store elements of the same type.

Which syntax correctly defines a list containing mixed data types?

collection = (1, 'two', 3.0)

list = [1, 2, 3, 4]

my_list = {1, 'two', 3.0}

a = [99, 'bottles of water ', ['on', 'the', 'wall']] (correct)

What will be the output of the following code: `a = [0, 1, 2, 3, 4]; a.pop(0)`?

Error: Index out of range

[0, 1, 2, 3, 4]

[1, 2, 3, 4] (correct)

What does the `remove()` method do when applied to a list?

Removes the first occurrence of a specified element. Signup and view all the answers

Which of the following operations cannot be performed on a Python list?

Directly assigning a new value to the list itself. Signup and view all the answers

What will be the output of `len(a)` after executing `a = [1, 2, 3]; a.append(4)`?

4 Signup and view all the answers

What is the result of `a = range(5); a.sort()`?

[0, 1, 2, 3, 4] Signup and view all the answers

When would a ValueError be raised in relation to list operations?

When calling <code>remove()</code> with an element not in the list. Signup and view all the answers

What will be the output after executing the command `a.remove(2)` on the list `a = [1, 2, 3, 4, 5]`?

[1, 3, 4, 5] Signup and view all the answers

What happens when the `pop()` method is called without any arguments on the list `a = [1, 2, 3, 4, 5]`?

It returns 5 and removes it from the list. Signup and view all the answers

What error is thrown when `a.pop(100)` is executed on the list `a = [1, 2, 3, 4, 5]`?

IndexError Signup and view all the answers

What does the variable `u` equal when executed as `u = [t, 2, t]`, given `t = ['begin', s, 'end']`?

['begin', [1, 2, 3], 'end', 2, 'begin', [1, 2, 3], 'end'] Signup and view all the answers

How are dictionary items presented?

In unordered key:value pairs. Signup and view all the answers

Which of the following statements is true about keys in a dictionary?

Keys should be unique within a dictionary. Signup and view all the answers

What type of brackets are used to define a dictionary?

Curly brackets Signup and view all the answers

What value will be returned when `thisdict['brand']` is accessed from the `thisdict` example given?

Ford Signup and view all the answers

What will the code `print(thisdict)` output after executing `thisdict = {'brand': 'Ford', 'model': 'Mustang', 'year': 1964, 'year': 2020}`?

{'brand': 'Ford', 'model': 'Mustang', 'year': 2020} Signup and view all the answers

What does the `clear()` method do when called on a dictionary?

Removes all elements from the dictionary. Signup and view all the answers

Which of the following methods would return the keys of a dictionary?

keys() Signup and view all the answers

What will `thisdict.get('model')` return assuming `thisdict` contains {'brand': 'Ford', 'model': 'Mustang', 'year': 1964}?

'Mustang' Signup and view all the answers

What is the output of `thisdict.items()` for the dictionary `thisdict = {'brand': 'Ford', 'model': 'Mustang', 'year': 1964}`?

[('brand', 'Ford'), ('model', 'Mustang'), ('year', 1964)] Signup and view all the answers

What does the `copy()` method do when applied to a dictionary?

Returns a shallow copy of the dictionary. Signup and view all the answers

Which method would you use to remove an item with a specified key from a dictionary?

pop() Signup and view all the answers

What is the output of `thisdict.values()` for `thisdict = {'brand': 'Ford', 'model': 'Mustang', 'year': 1964}`?

['Ford', 'Mustang', 1964] Signup and view all the answers

If `thisdict` is defined as `{'brand': 'Ford', 'model': 'Mustang', 'year': 1964}`, what will `thisdict.setdefault('new_key', 'new_value')` return?

'new_value' with key 'new_key' added Signup and view all the answers

What will be the output of the following code: `thisdict = {'brand': 'Ford', 'model': 'Mustang', 'year': 1964}; x = thisdict.setdefault('model', 'Toyota'); print(x)`?

Mustang Signup and view all the answers

What happens when you use the `setdefault` method with a key that does not exist in the dictionary?

It inserts the key with the specified value Signup and view all the answers

What will the dictionary look like after executing `thisdict.update({'year': 1990})` on `thisdict = {'brand': 'Ford', 'model': 'Mustang', 'year': 1964}`?

{'brand': 'Ford', 'model': 'Mustang', 'year': 1990} Signup and view all the answers

What is the output of `thisdict.has_key('country')` if `thisdict = {'brand': 'Ford', 'model': 'Mustang', 'year': 1964}`?

False Signup and view all the answers

Which method can be used to check if a specific key is present within a dictionary?

has_key() Signup and view all the answers

Study Notes

Network Programming: Data Types in Python

The presentation covers Python data types, focusing on lists and dictionaries.

Agenda

The agenda includes: introduction to Python, running Python, Python programming, data types, control flows, classes, functions, modules, and hands-on exercises.

Compound Data Type: List

Lists are containers holding multiple objects.
Lists are ordered collections of objects.
Lists are defined using square brackets.
Example List definition: a = [1, 2, 3, 4, 5]
Example retrieving specific element from a list: print a[1] which returns 2
Example: some_list.append("foo") adds element to the list
Example of list length: print len(some_list)

List Operations

Lists are flexible, acting like dynamic arrays.
They support the same operators as strings.
List operations: a+b, a*3, a[0], a[-1], a[1:], len(a)
Item and slice assignment is possible, e.g., a[0] = 98, a[1:2] = ["bottles", "of", "water"].
The del statement can be used for list element removal, e.g., del a[-1]
Supported operations include: append, insert, index, count, sort, reverse, remove, pop, and extend.

More List Operations

Demonstrates usage of Python list methods like appending, popping, inserting elements at an index, reversing list order, and sorting list elements.

Operations in List

The various operations supported in Python list data structure, including indexing, slicing, concatenation, repetition, membership test and retrieving length. Example L[1:5] (slicing) L + L (concatenation), len(L) for the length of a list.

Methods in List

remove(): removes element with the specified value (throws error if element not found).
pop(): removes and returns the element in index number, optionally taking an integer.
Examples of removing items from a list and the use of remove and pop method on lists a = [1, 2, 3, 4, 5], a.remove(2), and a.pop()/ a.pop(1). Example where error arises when trying to remove a non-existent value like in this case a.remove(100), the behavior is explained.

Nested List

A nested list is a list within a list.
Example: A list containing a list.

Dictionaries

Dictionaries are key-value pairs.
Dictionaries are unordered collections of key-value pairs.
Dictionaries are defined using curly brackets {}.
Examples of creating a dictionary thisdict = {"brand": "Ford", "model": "Mustang", "year": 1964}

Dictionary Items

Dictionary items are changeable, adding or removing items is possible after dictionary creation.
Dictionaries cannot have two items with the same key.

Dictionary Methods

clear(): Removes all elements from a dictionary.
copy(): Creates a copy of a specified dictionary.
get(key): Returns the value for the specified key (handles non-existent keys).
items(): Returns a list of tuples, where each tuple contains a key-value pair.
keys(): Returns a list containing all keys in the dictionary.
values(): Returns a list of all values in the dictionary.
pop(): Removes the item with the specified key and returns its value.
setdefault(key, value): Returns the value of the key. If the key doesn't exist, the key is inserted with the value specified.
update(): Updates the dictionary with the key-value pairs from another dictionary or an iterable of key-value pairs.
has_key(key) : Checks if a key exists in a dictionary, this method is deprecated, therefore shouldn't be used

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Description

This quiz covers the essential data types in Python, focusing specifically on lists and dictionaries. You'll learn about list operations, definitions, and their flexible nature as dynamic arrays, along with examples and hands-on exercises. Test your knowledge on these fundamental data structures in Python programming.

Network Prog Ch 2: Python Data Types

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Podcast

Questions and Answers

What is a list in Python?

Which syntax correctly defines a list containing mixed data types?

What will be the output of the following code: a = [0, 1, 2, 3, 4]; a.pop(0)?

What does the remove() method do when applied to a list?

Which of the following operations cannot be performed on a Python list?

What will be the output of len(a) after executing a = [1, 2, 3]; a.append(4)?

What is the result of a = range(5); a.sort()?

When would a ValueError be raised in relation to list operations?

What will be the output after executing the command a.remove(2) on the list a = [1, 2, 3, 4, 5]?

What happens when the pop() method is called without any arguments on the list a = [1, 2, 3, 4, 5]?

What error is thrown when a.pop(100) is executed on the list a = [1, 2, 3, 4, 5]?

What does the variable u equal when executed as u = [t, 2, t], given t = ['begin', s, 'end']?

How are dictionary items presented?

Which of the following statements is true about keys in a dictionary?

What type of brackets are used to define a dictionary?

What value will be returned when thisdict['brand'] is accessed from the thisdict example given?

What will the code print(thisdict) output after executing thisdict = {'brand': 'Ford', 'model': 'Mustang', 'year': 1964, 'year': 2020}?

What does the clear() method do when called on a dictionary?