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Questions and Answers
A tuple can be modified after it has been created.
A tuple can be modified after it has been created.
False
The median can be calculated from a list of numbers by sorting it and finding the middle value.
The median can be calculated from a list of numbers by sorting it and finding the middle value.
True
The return statement in a function is used to end the function's execution and send a value back to the caller.
The return statement in a function is used to end the function's execution and send a value back to the caller.
True
A list in Python is a fixed-size collection that cannot grow or shrink.
A list in Python is a fixed-size collection that cannot grow or shrink.
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A function's docstring can be viewed by using the help function.
A function's docstring can be viewed by using the help function.
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The syntax for defining a function in Python always requires parentheses, even if there are no parameters.
The syntax for defining a function in Python always requires parentheses, even if there are no parameters.
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Dictionaries in Python are ordered collections of items stored as key-value pairs.
Dictionaries in Python are ordered collections of items stored as key-value pairs.
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The '+' operator can be used to concatenate two tuples in Python.
The '+' operator can be used to concatenate two tuples in Python.
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A parameter is the name used in the function definition for an argument passed to the function.
A parameter is the name used in the function definition for an argument passed to the function.
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In Python, a function can return multiple values without using a return statement.
In Python, a function can return multiple values without using a return statement.
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A Boolean function always returns either True or False based on the properties of its argument.
A Boolean function always returns either True or False based on the properties of its argument.
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The special value returned by a function that has no return statement is called Null.
The special value returned by a function that has no return statement is called Null.
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Functions defined with no parameters expect at least one argument when called.
Functions defined with no parameters expect at least one argument when called.
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The syntax of a return statement in Python is simply 'return'.
The syntax of a return statement in Python is simply 'return'.
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The return value of a function is determined by the parameters passed to it.
The return value of a function is determined by the parameters passed to it.
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To explicitly return a value from a function, a return statement should be placed at every exit point of that function.
To explicitly return a value from a function, a return statement should be placed at every exit point of that function.
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The main function in Python usually expects one argument and returns a value.
The main function in Python usually expects one argument and returns a value.
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In Python, dictionaries organize data by their position in the structure.
In Python, dictionaries organize data by their position in the structure.
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The entry point for program execution in Python is denoted by the statement 'if name == main'.
The entry point for program execution in Python is denoted by the statement 'if name == main'.
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Data structures organized by association are also known as lists.
Data structures organized by association are also known as lists.
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Functions in Python can be defined in any order as long as the main function is called at the end of the script.
Functions in Python can be defined in any order as long as the main function is called at the end of the script.
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In the example provided, the square function is defined to return the cube of a number.
In the example provided, the square function is defined to return the cube of a number.
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A dictionary in Python associates a set of keys with corresponding data values.
A dictionary in Python associates a set of keys with corresponding data values.
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The first step in defining a main function in Python is to include a comment about its purpose.
The first step in defining a main function in Python is to include a comment about its purpose.
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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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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.
