Python Fundamentals: Lists and Dictionaries
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Questions and Answers

A tuple can be modified after it has been created.

False (B)

The median can be calculated from a list of numbers by sorting it and finding the middle value.

True (A)

The return statement in a function is used to end the function's execution and send a value back to the caller.

True (A)

A list in Python is a fixed-size collection that cannot grow or shrink.

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

A function's docstring can be viewed by using the help function.

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

The syntax for defining a function in Python always requires parentheses, even if there are no parameters.

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

Dictionaries in Python are ordered collections of items stored as key-value pairs.

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

The '+' operator can be used to concatenate two tuples in Python.

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

A parameter is the name used in the function definition for an argument passed to the function.

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

In Python, a function can return multiple values without using a return statement.

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

A Boolean function always returns either True or False based on the properties of its argument.

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

The special value returned by a function that has no return statement is called Null.

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

Functions defined with no parameters expect at least one argument when called.

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

The syntax of a return statement in Python is simply 'return'.

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

The return value of a function is determined by the parameters passed to it.

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

To explicitly return a value from a function, a return statement should be placed at every exit point of that function.

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

The main function in Python usually expects one argument and returns a value.

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

In Python, dictionaries organize data by their position in the structure.

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

The entry point for program execution in Python is denoted by the statement 'if name == main'.

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

Data structures organized by association are also known as lists.

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

Functions in Python can be defined in any order as long as the main function is called at the end of the script.

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

In the example provided, the square function is defined to return the cube of a number.

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

A dictionary in Python associates a set of keys with corresponding data values.

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

The first step in defining a main function in Python is to include a comment about its purpose.

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

Flashcards

Function Parameter

The name used in a function definition for an argument passed to it.

Function Argument

The actual value passed to a function's parameter when the function is called.

Return Statement

A statement that specifies the value a function returns.

Function with No Return

A function without an explicit return statement.

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Boolean Function

A function that returns either True or False based on a condition.

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Odd number function

A function that checks if a number is odd.

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Matching Parameters and Arguments

The number and positions of arguments in a function call must match the parameters in the function definition.

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Implicit Return

Functions without a return statement return the value None.

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Calculating Median

The median is the middle value in a sorted list of numbers. If the list has an odd number of elements, the median is the middle element. If the list has an even number of elements, the median is the average of the two middle elements.

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Tuple

A tuple is an ordered, immutable sequence of items. Tuples are similar to lists, but their contents cannot be changed after creation.

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Immutable Sequence

An immutable sequence is a data structure that stores elements in a specific order, and once created, the elements cannot be changed.

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Function Definition

A block of code that performs a specific task. It is defined using the def keyword followed by the function name and parentheses.

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Docstring

A string used to document a function, it explains what the function does. Place inside triple quotes.

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Function Header

The first part of a function definition, which includes the keyword 'def', the function name, parentheses, and arguments (variables receiving data).

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Function Body

The part of a function containing the code that performs the task described in the function's docstring.

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Return Value

The output produced by a function which represents the result, if any. It's the value given back from the function.

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Main Function

The starting point of a Python script's execution.

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Python Script Execution

Python code runs from a main function, typically by calling it.

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Dictionaries

Data structures in Python which store information by associating keys and values.

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Key-Value Pairs

The way data is stored in a dictionary, connecting a key to a value.

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Association Lists

Another name for dictionaries that organize data based on associations.

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Script Order

Defining functions (including main) doesn't dictate the script's execution order; the import or call of main is critical.

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Data Structure

A structured way to store and organize data.

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Python Dictionaries

Used to store data values associated with unique keys.

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Study Notes

Fundamentals of Python: First Programs

  • Second Edition, Chapter 5 focuses on Lists and Dictionaries.

Objectives (Part 1)

  • Construct lists and access items within them
  • Use methods to manipulate lists
  • Complete traversals of lists to process list items
  • Define simple functions accepting parameters and returning values

Objectives (Part 2)

  • Construct dictionaries and access entries
  • Employ methods to manipulate dictionaries
  • Determine if a list or dictionary is suitable for a given application

Introduction

  • Lists are sequences of data, handling any data type.
  • Dictionaries associate data values by relationship rather than position.
  • Both offer powerful ways to organize data.

Lists

  • Lists represent sequences of items (elements).
  • Examples: Grocery lists, to-do lists, rosters, recipes, etc.
  • Each item has a unique index (0 to length-1).

List Literals and Basic Operators

  • Examples of list literals: ['apples', 'oranges', 'cherries'], [[5, 9], [541, 78]]
  • Expressions within lists evaluate to a value.
  • The 'len' function returns the length of a list; square brackets access elements by index.
  • Concatenation (+) and equality (==) are supported; Python handles integer ranges effectively.

List Methods (Part 1)

  • Method append adds an element to the end of a list.
  • Method extend adds multiple elements from another list to the end.
  • Method insert inserts an element at a specified index.

List Methods (Part 2)

  • Method pop removes and returns an element from the end of the list; pop(index) removes and returns an element at the specified index.

Searching a List

  • Operator 'in' checks if an element exists in a list.
  • Using the .index() method finds an element's index.

Sorting a List

  • Data is ordered by position in a list
  • Data can be sorted alphabetically or numerically
  • Use the method sort to modify a list.

Mutator Methods and the Value None

  • Methods like insert, append, extend, pop, and sort modify lists directly, usually returning None.

Aliasing and Side Effects

  • Variables referencing the same list object are aliases.
  • Modifying one element in one alias affects other aliases.
  • Create new lists to avoid unintended side effects.

Equality: Object Identity and Structural Equivalence

  • The == operator checks if two objects have the same values.
  • The is operator evaluates if two variables reference the same object in memory.

Dictionaries

  • Data organized by associations (key-value pairs)
  • Examples: phone books, personal information.
  • Keys are immutable (e.g., strings, integers), used to access values.

Adding Keys and Replacing Values

  • Use square brackets [] to add or replace key/value pairs.

Accessing Values

  • Access dictionary values with [].
  • Use d.get() method to avoid errors if a key doesn't exist (optional).

Removing Keys

  • Using the pop() method, remove and return a value associated with a key.

Traversing Dictionaries

  • Loops are used to get all keys and values.
  • The .items() method iterates through key-value pairs as tuples.

Dictionary Operations (Methods)

  • len(d): Returns the number of entries (key-value pairs).
  • d[key]: Returns the value associated with the key.
  • d.get(key [, default]): Returns the value or a default value.
  • d.pop(key [, default]): Removes and returns the value if the key exists.
  • list(d.keys()): Returns a list of keys,
  • list(d.values()): Returns a list of values.
  • list(d.items()): Returns a list of key-value pairs (tuples).
  • d.clear(): Removes all keys and values.

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Python Fundamentals: Lists and Dictionaries PDF

Description

Explore Chapter 5 of the second edition, focusing on the construction and manipulation of lists and dictionaries in Python. Learn how to access items, use methods for data handling, and understand suitable applications for these data structures through various examples.

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