Matlab File I/O & Data Importing Quiz

When working with a mixed-type dataset containing both text and numeric columns in a CSV file, which MATLAB function is most appropriate to preserve the column headers and data types?

You have a large matrix of numeric data stored in an Excel file named 'data.xlsx' in the sheet 'RawData'. How would you import just this numeric data into a double-precision array?

% File: data.xlsx contains multiple sheets
% Sheet 'RawData' has numeric values

% Goal: Import only the numeric matrix

What is the primary advantage of using MATLAB's native .mat file format compared to CSV or text files?

You need to save only the variables 'results' and 'config' from your current workspace to a file named 'experiment_final.mat'. Which command achieves this?

>> whos
  Name       Size            Bytes  Class
  data       1000x1000     8000000  double
  config     1x1               500  struct
  results    100x1             800  double
  temp_var   1x1                 8  double

When using the Import Tool in MATLAB, what is a key benefit of generating a script or function from your interactive selection?

How does the fullfile function contribute to writing robust MATLAB code?

folder = 'C:\Data';
file = 'experiment.csv';
path = fullfile(folder, file);

You are processing a list of CSV files in a directory. Which command would you use to get a struct array containing information about all files matching the pattern '*.csv'?

What is the default behavior of the load command when used on a .mat file without assigning output variables?

>> load('mydata.mat')

You have a table T and want to export it to a CSV file named 'output.csv'. Which function is the most direct way to do this?

Consider the following code snippet. What will be the content of the variable 'data'?

% File 'config.txt' contains:
% 100
% 200
% 300

fID = fopen('config.txt', 'r');
data = fscanf(fID, '%d');
fclose(fID);

Why might you choose to use readtable over readmatrix when importing a CSV file?

You are writing a script that needs to read a file located two levels up from the current script's directory. Which command correctly constructs this path?

% Current location: /Project/Code/Scripts/
% Target file: /Project/Data/input.mat

What happens if you try to use load on a file that is not in the current folder or the MATLAB search path?

You have a matrix A and want to append it to an existing text file 'log.txt' without overwriting the previous content. Which approach is valid?

A = [1 2 3];
% Goal: Append A to 'log.txt'

What is the purpose of the 'VariableNamingRule' parameter in readtable?

Which command would you use to verify if a specific file exists before attempting to read it?

filename = 'data.csv';
if ______
    data = readtable(filename);
else
    warning('File not found');
end

When using writetable to export data to Excel, how can you specify the worksheet name?

You have imported a large dataset into a table 'T'. You want to save this table to a binary .mat file for faster loading next time. What is the command?

What does the 'DetectImportOptions' function do?

You are reading a text file where data fields are separated by semicolons instead of commas. How do you handle this with readtable?

% File: data.txt
% Name;Age;Score
% Alice;25;90

Which function allows you to read a specific range of cells from an Excel file, such as 'B2:D10'?

What is the result of using the 'TextType', 'string' option in readtable?

You need to create a new folder named 'Output' to store your results. Which command does this?

When using low-level file I/O with fopen, what does the permission 'w' signify?

fid = fopen('results.txt', 'w');

How can you close a file handle 'fid' after you are done writing to it?

You want to save a figure currently displayed in Figure 1 to a PNG image file. Which command is appropriate?

What is the function of the 'whos' command with the '-file' flag?

>> whos -file mydata.mat

Which command allows you to interactively select a file from the operating system's file dialog box?

You have a cell array of strings 'C' and want to write it to a text file, line by line. Which low-level approach is correct?

C = {'Line 1', 'Line 2', 'Line 3'};
fid = fopen('output.txt', 'w');
for i = 1:length(C)
    ______
end
fclose(fid);

What is a potential issue when using absolute file paths (e.g., 'C:\Users\Name\Project\data.csv') in your code?

How do you read a CSV file that has 5 header lines that need to be skipped?

What is the difference between 'save' and 'save -v7.3'?

You want to load data from a file, but the filename is stored in a variable. Which syntax is correct?

fname = 'experiment_01.mat';

Which function would you use to read an image file (like .jpg or .png) into a numeric array?

You have a structure 'S' and you want to save it to a .mat file such that the fields of S become individual variables in the file. How do you do this?

What does the command 'type filename.m' do in the Command Window?

You are reading a file and want to ensure the file handle is closed even if an error occurs during reading. What structure should you use?

fid = fopen('data.txt');
try
    % Read data
    data = fread(fid);
catch
    % Handle error
end
______ % Ensure close

Which command returns the current working directory?

You want to read a JSON file into a MATLAB structure. Which function should you use?

When using 'readtable', how can you handle missing data in the file automatically?