CSV file handling in MATLAB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Reading CSV with readmatrix

What is the output of this MATLAB code when reading a CSV file with numeric data only?

MATLAB

data = readmatrix('data.csv');
disp(data);

A [1 2 3; 4 5 6; 7 8 9]

B Error: File not found

C A cell array with numeric and text data

D A table with variable names

💡 Hint

readmatrix reads numeric data into a numeric array.

readmatrix reads numeric CSV data into a numeric matrix. If the file contains only numbers, the output is a numeric array.

❓ Predict Output

intermediate

Writing CSV with writematrix

What will be the content of 'output.csv' after running this MATLAB code?

MATLAB

M = [10 20 30; 40 50 60];
writematrix(M, 'output.csv');

A A CSV file with text headers

B A CSV file with one row: '10 20 30 40 50 60'

C An empty file

D A CSV file with two rows: '10,20,30' and '40,50,60'

💡 Hint

writematrix writes numeric arrays as CSV rows.

writematrix writes each row of the matrix as a line in the CSV file, with commas separating values.

🔧 Debug

advanced

Reading mixed data CSV with readmatrix

What is the result of this MATLAB code when reading a CSV file with mixed text and numbers using readmatrix?

MATLAB

data = readmatrix('mixed.csv');

A Returns a table with mixed data

B Error: Unable to convert text to numeric

C No error, returns numeric matrix with NaN for text

D Error: File not found

💡 Hint

readmatrix converts non-numeric data to NaN.

readmatrix reads the file into a numeric matrix, replacing text or non-numeric data with NaN. No error occurs.

❓ Predict Output

advanced

Reading CSV with readtable and accessing data

Given a CSV file 'people.csv' with columns 'Name,Age,Height', what is the output of this code?

MATLAB

T = readtable('people.csv');
disp(T.Age(2));

A The entire Age column

B The age value of the second person in the table

C Error: Age is not a field

D The name of the second person

💡 Hint

readtable creates a table with column names as fields.

readtable reads CSV into a table. Accessing T.Age(2) returns the second row's Age value.

🧠 Conceptual

expert

Choosing the best function for mixed CSV data

Which MATLAB function is best suited to read a CSV file containing both numeric and text data with headers?

A readtable

B readmatrix

C writematrix

D csvread

💡 Hint

Consider which function handles mixed data and headers well.

readtable reads CSV files with mixed data types and headers into a table, preserving data types and column names.