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)
  • 0

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

<p>Removes the first occurrence of a specified element. (A)</p> Signup and view all the answers

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

<p>Directly assigning a new value to the list itself. (D)</p> Signup and view all the answers

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

<p>4 (D)</p> Signup and view all the answers

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

<p>[0, 1, 2, 3, 4] (A)</p> Signup and view all the answers

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

<p>When calling <code>remove()</code> with an element not in the list. (A)</p> 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]?

<p>[1, 3, 4, 5] (B)</p> 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]?

<p>It returns 5 and removes it from the list. (B)</p> 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]?

<p>IndexError (A)</p> Signup and view all the answers

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

<p>['begin', [1, 2, 3], 'end', 2, 'begin', [1, 2, 3], 'end'] (A)</p> Signup and view all the answers

How are dictionary items presented?

<p>In unordered key:value pairs. (D)</p> Signup and view all the answers

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

<p>Keys should be unique within a dictionary. (A)</p> Signup and view all the answers

What type of brackets are used to define a dictionary?

<p>Curly brackets (B)</p> Signup and view all the answers

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

<p>Ford (B)</p> Signup and view all the answers

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

<p>{'brand': 'Ford', 'model': 'Mustang', 'year': 2020} (B)</p> Signup and view all the answers

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

<p>Removes all elements from the dictionary. (D)</p> Signup and view all the answers

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

<p>keys() (D)</p> Signup and view all the answers

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

<p>'Mustang' (A)</p> Signup and view all the answers

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

<p>[('brand', 'Ford'), ('model', 'Mustang'), ('year', 1964)] (D)</p> Signup and view all the answers

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

<p>Returns a shallow copy of the dictionary. (D)</p> Signup and view all the answers

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

<p>pop() (D)</p> Signup and view all the answers

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

<p>['Ford', 'Mustang', 1964] (D)</p> 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?

<p>'new_value' with key 'new_key' added (C)</p> 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)?

<p>Mustang (D)</p> Signup and view all the answers

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

<p>It inserts the key with the specified value (A)</p> 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}?

<p>{'brand': 'Ford', 'model': 'Mustang', 'year': 1990} (D)</p> Signup and view all the answers

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

<p>False (B)</p> Signup and view all the answers

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

<p>has_key() (B)</p> Signup and view all the answers

Flashcards

List Data Type

A collection of items (objects) arranged in a specific order. It is mutable, meaning you can modify its contents after creation.

List Creation

Lists are created using square brackets [] and elements are separated by commas. Example: [ 1, 'apple', 'banana' ]

List Access (Indexing)

Accessing elements in a list is done by their position (index), starting from 0. Example: my_list[0] will give the first element.

List Slicing

Selecting a range of elements from a list using colon (:). Example: my_list[1:3] will give the elements from the second to the third element.

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List Append

Adding an element to the end of a list.

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List Insert

Adding an element at a specific index in a list.

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List Remove

Deleting an element from a list by its value.

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List Pop

Deleting an element from a list by its index, returning the deleted element.

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Dictionary Access

Retrieving a value associated with a specific key in a dictionary.

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Dictionary Modification

Changing, adding, or removing items (key-value pairs) within a dictionary after it's created.

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Dictionary Clear Method

Removes all items from a dictionary, making it an empty dictionary.

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Dictionary Copy Method

Creates a separate copy of a dictionary, allowing you to modify the copy without affecting the original dictionary.

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Dictionary Get Method

Retrieves the value associated with a specific key, returning 'None' if the key is not found.

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Dictionary Items Method

Returns a list of tuples where each tuple represents a key-value pair from the dictionary.

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Dictionary Keys Method

Returns a list containing all the keys of the dictionary, representing the titles of the books on the shelf.

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Dictionary Values Method

Returns a list of all the values present in the dictionary, representing the contents of the books on the shelf.

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Dictionary Pop Method

Removes the item (key-value pair) associated with a specific key from the dictionary.

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Dictionary Setdefault Method

Returns the value of the specified key. If the key is not found, it adds the key with the specified value to the dictionary.

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setdefault() method

The setdefault() method checks if a specified key exists in the dictionary. If the key exists, it returns the corresponding value. If the key doesn't exist, it inserts the key with the specified value and returns the value.

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Updating a dictionary with setdefault()

When using setdefault(), if the key doesn't exist, the dictionary is updated by inserting the new key-value pair. If the key already exists, the dictionary remains unchanged.

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update() method

The update() method modifies an existing dictionary by adding or replacing key-value pairs from another dictionary or a set of key-value pairs.

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has_key() method

The has_key() method checks if a specified key exists in the dictionary and returns True if it does, False otherwise.

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Key-value pairs

A key-value pair is a fundamental element within a dictionary. It consists of a unique key and its associated value. Keys are used to access and retrieve their corresponding values.

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Nested Lists

A nested list is a list that contains other lists as elements.

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Dictionary

A dictionary is an unordered collection of key-value pairs. It stores data in a way that allows you to access values using unique keys.

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Dictionary Key

A key in a dictionary uniquely identifies a value. It's like a label for a piece of data.

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Dictionary Value

The value in a dictionary is the data associated with a key. It's the information stored and accessed using the key.

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Dictionary Features

Dictionaries have three key features: unordered, changeable, and do not allow duplicates. This means their order doesn't matter, they can be modified after creation, and each key is unique.

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Accessing Dictionary Values

To retrieve a value from a dictionary, use its corresponding key within square brackets [] after the dictionary name.

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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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Python Data Types Lecture Notes PDF

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.

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