Excel file reading and writing in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What MATLAB function is used to read data from an Excel file?

The readtable function is commonly used to read data from an Excel file into a table format.

beginner

How do you write a MATLAB table to an Excel file?

Use the writetable function to write a table to an Excel file.

intermediate

What argument do you use with readtable to specify a sheet name?

Use the 'Sheet' name-value pair argument, for example: readtable('file.xlsx', 'Sheet', 'Sheet2').

intermediate

How can you read only a specific range of cells from an Excel file in MATLAB?

Use the 'Range' argument with readtable, for example: readtable('file.xlsx', 'Range', 'A1:C10').

intermediate

What happens if you use writetable on an existing Excel file?

The default sheet ('Sheet1') is overwritten (other sheets preserved) unless you specify a different sheet or file name.

Which MATLAB function reads data from an Excel file into a table?

A readtable

B xlswrite

C csvread

D writetable

readtable reads Excel data into a table. xlswrite writes data, csvread reads CSV files, and writetable writes tables.

How do you specify which sheet to read from in an Excel file using MATLAB?

A Using the 'Sheet' argument in readtable

B Using the 'Range' argument in writetable

C Using the 'Sheet' argument in writetable

D Using the 'Range' argument in readtable

The 'Sheet' argument in readtable lets you choose the sheet to read.

What does the 'Range' argument do in readtable?

A Specifies the delimiter

B Specifies the sheet name

C Specifies the output file name

D Specifies the cells to read from the Excel sheet

The 'Range' argument limits reading to a specific cell range like 'A1:C10'.

Which function writes a MATLAB table to an Excel file?

A xlsread

B readtable

C writetable

D csvwrite

writetable writes tables to Excel files. readtable reads tables.

What happens if you write to an existing Excel file with writetable without specifying a sheet?

A The data is appended

B The default sheet ('Sheet1') is overwritten

C An error occurs

D The file is renamed automatically

By default, writetable overwrites the default sheet ('Sheet1') in the existing Excel file (other sheets are preserved).

Explain how to read data from a specific sheet and range in an Excel file using MATLAB.

Think about how to tell MATLAB which part of the Excel file to read.

Describe the process to write a MATLAB table to an Excel file and what happens if the file already exists.

Consider what happens by default and how to avoid overwriting.

Practice

1. Which MATLAB function is used to read data from an Excel file into a table?

easy

A. csvread

B. xlswrite

C. readtable

D. load

Solution

1. Step 1: Identify the function for reading Excel files

   MATLAB provides readtable to import Excel data as a table.

2. Step 2: Differentiate from other functions

   xlswrite writes data, csvread reads CSV files, and load loads MAT files.

3. Final Answer:

   readtable -> Option C

4. Quick Check:

   Excel read function = readtable [OK]

Hint: Use readtable to import Excel data as tables quickly [OK]

Common Mistakes:

• Confusing readtable with xlswrite
• Using csvread for Excel files
• Trying to use load for Excel data

2. Which of the following is the correct syntax to write a table T to an Excel file named data.xlsx?

easy

A. readtable('data.xlsx', T)

B. write(T, 'data.xlsx')

C. xlsread('data.xlsx', T)

D. writetable(T, 'data.xlsx')

Solution

1. Step 1: Identify the correct function for writing tables

   The function writetable writes tables to Excel files.

2. Step 2: Check the syntax

   The syntax is writetable(T, 'filename.xlsx'). Other options are either reading functions or incorrect.

3. Final Answer:

   writetable(T, 'data.xlsx') -> Option D

4. Quick Check:

   Write table syntax = writetable(T, filename) [OK]

Hint: Use writetable with table and filename to save Excel files [OK]

Common Mistakes:

• Using write instead of writetable
• Confusing xlsread with writing
• Passing table as second argument to readtable

3. What will be the output of the following MATLAB code?

T = readtable('sales.xlsx', 'Sheet', 'Q1', 'Range', 'A1:C5');
disp(height(T));

medium

A. 4

B. 5

C. 3

D. 6

Solution

1. Step 1: Understand the readtable range and header

   The range 'A1:C5' includes 5 rows, but the first row is usually the header.

2. Step 2: Calculate the number of data rows

   Since the first row is header, the data rows are 5 - 1 = 4.

3. Final Answer:

   4 -> Option A

4. Quick Check:

   Rows read minus header = 4 [OK]

Hint: Remember first row is header, so data rows = total rows - 1 [OK]

Common Mistakes:

• Counting header row as data
• Confusing range size with number of rows
• Assuming no header row present

4. Identify the error in this MATLAB code snippet that tries to write a table T to the second sheet of results.xlsx:

writetable(T, 'results.xlsx', 'Sheet', 2, 'Range', 'B2');

medium

A. The 'Sheet' parameter must be a string, not a number

B. The 'Range' parameter cannot be used with writetable

C. The filename must include full path

D. writetable cannot write to Excel files

Solution

1. Step 1: Check the 'Sheet' parameter type

   In writetable, the 'Sheet' argument should be a string with sheet name, not a numeric index.

2. Step 2: Validate other parameters

   'Range' is valid, filename can be relative, and writetable supports Excel files.

3. Final Answer:

   The 'Sheet' parameter must be a string, not a number -> Option A

4. Quick Check:

   Sheet name must be string in writetable [OK]

Hint: Use sheet names as strings, not numbers, in writetable [OK]

Common Mistakes:

• Passing sheet number instead of name
• Thinking Range is invalid for writetable
• Assuming filename needs full path always

5. You want to read only the numeric data from the range B2:D10 in sheet Data of metrics.xlsx into MATLAB as a table. Which code snippet correctly does this and then writes only the first 5 rows back to a new Excel file subset.xlsx?

hard

A. T = readmatrix('metrics.xlsx', 'Sheet', 'Data', 'Range', 'B2:D10');
writetable(T(1:5,:), 'subset.xlsx');

B. T = readtable('metrics.xlsx', 'Sheet', 'Data', 'Range', 'B2:D10');
writetable(T(1:5,:), 'subset.xlsx');

C. T = readtable('metrics.xlsx', 'Sheet', 'Data', 'Range', 'B2:D10');
writetable(T(1:5));

D. T = readmatrix('metrics.xlsx', 'Sheet', 'Data', 'Range', 'B2:D10');
writetable(T, 'subset.xlsx');

Solution

1. Step 1: Read numeric data as a table

   Use readtable with 'Sheet' and 'Range' to get data as a table.

2. Step 2: Write first 5 rows to new Excel file

   Use writetable with T(1:5,:) to write first 5 rows correctly.

3. Final Answer:

   T = readtable('metrics.xlsx', 'Sheet', 'Data', 'Range', 'B2:D10'); writetable(T(1:5,:), 'subset.xlsx'); -> Option B

4. Quick Check:

   readtable + subset rows + writetable = T = readtable('metrics.xlsx', 'Sheet', 'Data', 'Range', 'B2:D10'); writetable(T(1:5,:), 'subset.xlsx'); [OK]

Hint: Use readtable with range, then slice rows before writetable [OK]

Common Mistakes:

• Using readmatrix but then writetable on matrix
• Omitting filename in writetable
• Not slicing rows correctly before writing