MATLAB Structures Unit 5

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Questions and Answers

What happens when you assign a value to a new field in a structure in MatLab?

The structure is entirely rebuilt.

The existing fields are deleted.

No changes occur to the structure.

The structure is extended to accommodate the new field. (correct)

Which function would you use to display a structure in its default format in MatLab?

show()

printStruct()

displayStruct()

disp() (correct)

Which of the following is a good programming practice when defining structures in MatLab?

Extending structures without prior declaration.

Using the struct() function. (correct)

Using arrays for all data management.

Defining them without field names.

What type of data can fields within a structure contain?

Any type of data, including nested structures and arrays. Signup and view all the answers

What would the output be for the following fprintf command: fprintf('Price: %.2f euro ', myFlight.ticketPrice); where myFlight.ticketPrice is 145.99?

Price: 145.99 euro Signup and view all the answers

What is the primary purpose of a structure in MATLAB?

To group heterogenous but logically related data Signup and view all the answers

Which of the following best describes how to create a structure in MATLAB?

By explicitly using the struct function Signup and view all the answers

How do you access a specific field within a structure in MATLAB?

Applying the dot operator Signup and view all the answers

What is a significant feature of structures compared to arrays in MATLAB?

Each field in a structure can be of a different data type. Signup and view all the answers

When creating a structure called 'myFlight', which of the following is an example of an implicit extension method?

myFlight.origin = 'MAD'; Signup and view all the answers

What is the purpose of using nested structures in MATLAB?

To allow a field to contain another structure. Signup and view all the answers

Which command changes the altitude of the position field within the myFlight structure?

myFlight.details.position.altitude = 11582; Signup and view all the answers

In the student structure, how are the marks stored?

As an array of values. Signup and view all the answers

Which part of the structure myFlight contains information regarding the flight's speed?

details Signup and view all the answers

What does the command student.marks(6)=10; achieve in the student structure?

It sets the sixth mark to 10. Signup and view all the answers

What data structure is used to store multiple customers in the provided example?

Vector of structures Signup and view all the answers

Which operation is illustrated by the 'printAllCustomers' function?

Looping through a vector to print customer data Signup and view all the answers

What is the purpose of the 'randInitFlights' function?

To return a vector of flight structures with random values Signup and view all the answers

In the function 'printCustomer', what data type is expected as the input parameter?

Structure Signup and view all the answers

How can tables be indexed in MATLAB, as mentioned in the content?

By either name or numeric index Signup and view all the answers

What types of values are assigned to each flight structure in the 'randInitFlights' function?

A combination of strings and numeric values Signup and view all the answers

Which feature distinguishes tables in MATLAB from other data structures?

They can store different data types as long as row lengths are consistent. Signup and view all the answers

What is the likely output format for the 'printCustomer' function when displaying customer details?

Formatted text with labels Signup and view all the answers

What will be the value range for 'num_first_class' in the flight structure generated by 'randInitFlights'?

0 to 20 Signup and view all the answers

What is the purpose of the 'address' field in the student structure?

To hold a nested structure related to the student's country Signup and view all the answers

What is the primary advantage of using arrays of structures?

They help in managing and storing related information together. Signup and view all the answers

How would you access the marks of the first student in the array of structures?

students(1).marks(1) Signup and view all the answers

What is a recommended best practice when working with vectors of structures?

Pre-allocating memory and initializing contents. Signup and view all the answers

In the context of vectors of structures, which of the following statements is incorrect?

Arrays of structures require completely contiguous memory. Signup and view all the answers

How is the total stock value calculated in the array of products?

By multiplying each product’s amount by its unit price and summing the results. Signup and view all the answers

Which of the following best describes the access method used for values in structures?

Dot notation followed by index brackets. Signup and view all the answers

What type of data is commonly stored in an array of structures, as exemplified in the student data?

Various attributes related to an entity. Signup and view all the answers

During initialization of a vector of structures, which of the following is generally not required?

Declaring the total number of structures in advance. Signup and view all the answers

What is the purpose of using struct in the initialization of vProducts?

To define a data type that can hold multiple fields Signup and view all the answers

How can you initialize all elements of the vector vProducts in one line of code?

vProducts(1,1:4) = struct('name', '', ... 'amount', 0, ... 'price', 0); Signup and view all the answers

Which values are initialized to empty arrays in the given example?

amount, price, name Signup and view all the answers

What is the structure of the 'students' array as described?

It is a collection of structures with a defined number of fields. Signup and view all the answers

What type of initialization does 'marks' use in the students structure?

A vector of zeros with a fixed size Signup and view all the answers

What does the 'address' structure contain in the students initialization?

Fields for city and country Signup and view all the answers

In what scenario might initializing fields to an empty array be preferable?

When the number of elements is uncertain or variable Signup and view all the answers

Which initialization would result in multiple fields being set to empty string values in a single step?

struct('name', '', ... 'surname', '', ... 'age', 0) Signup and view all the answers

Study Notes

Unit 5: Structures

Structures are data types that group heterogeneous but logically related data using containers called fields
Structures are used to organize complex information in a program
Variables related logically can be treated as a single unit, rather than separate entities.
Each element (field) of a structure can have different data types
Used in MATLAB

Data Types in MATLAB

All variables in MATLAB are arrays
Data types include: Boolean, numeric (logical, floating-point, integer), text (char), and heterogeneous containers (name-based and index-based Structs, Cells, Tables)
Scalars are 1x1 arrays
Arrays are fundamental in MATLAB

Building Structures in MATLAB

Explicit: Using the struct function (recommended). Field names are enclosed in quotes.
Example: myFlight = struct('origin', 'MAD', 'destination', 'JFK', 'number', 'IB345', 'ticketPrice', 145.99);
Implicit: Extending by assignment. Values and fields are defined separately, but are not recommended as they can lead to errors or problems in other programming environments.

Accessing Structure Fields

Use the dot operator (.) to access a field of a structure.
The field name is used after the dot operator.
Example: myFlight.origin

Building/Extending Structures by Assignment

MATLAB builds structures from specified fields
Extends structures by assigning new fields (e.g., myFlight.airline = 'Iberia')

Displaying Structures

Displaying the structure shows all contents using the disp() function.
Using fprintf(), you can format the display.

Fields of a Structure

Fields can contain scalar data (integer, double, character), or other structures (nested structures) or arrays.

Nested Structures

Structures can contain other structures as fields.
Allows for complex data organization.
Example: myFlight.details.position.altitude.

Arrays of Structures

An array that includes structures as elements (e.g., students).
Useful for managing a collection of similar units with varying relevant data types.
Example: students(1).name.

Preallocating and Initializing Vectors of Structures

Pre-allocate memory for a collection of structures to improve efficiency, particularly with large data.
Initialize structures effectively to prevent performance issues and errors that may occur when dynamically allocating data.
Different methods in MATLAB, like explicit declaration of a structure or initialization to an empty array, to preallocate and initialize a vector for structures.

Functions As Parameters

Arrays and structure can be used as input parameters and output parameters of a function.

Other Structured Data Types (Annex)

Cell Arrays: Indexed containers that can hold data of different types (e.g., numbers, characters, other structures, or arrays). Braces {} are used
Tables: Column-oriented data arranged as a grid. Useful when organizing data in a tabular format, similar to spreadsheets.

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Description

This quiz covers Unit 5 on Structures in MATLAB, focusing on how structures are used to group heterogeneous data types logically. You'll learn about building structures explicitly and implicitly, as well as the various data types available in MATLAB. Test your understanding of how to organize complex information within the programming environment.