Matlab with excel data

Apply MATLAB analysis and visualization capabilities to Excel data

See also:

MATLAB provides options to write a table, array, or matrix to Microsoft Excel spreadsheets. The function available to do so is the writetable () function. The general syntax for this function is:

Syntax:

writetable(<data>, <filename>, <optional_values>)

Now, in the following sections, we shall see how to write a table, an array, and a matrix into a spreadsheet.

Writing a Table to Excel Spreadsheet:

Firstly, we shall create a table and then write the same to an excel spreadsheet with the help of writetable function.

Example 1: 

The output of the above code will create a new excel sheet in the current folder.

In the above code, we create a table from magic with the variable names or table headers passed as a vector. Then, in the writetable function, we pass the table, and the file name to be used (if present then, it’ll overwrite the data. If not, then it will create a new file and then, it’ll create a new file). The next argument is a field type that decides the file type and the argument following it is the value for the same field; spreadsheet in this case.

Writing a Matrix to Excel Spreadsheet

In the above section, we discussed how to add a table to an excel sheet. In this section, we shall explore the writetable further by adding a matrix at specified cells in a spreadsheet. Let us see the same with the help of an example. 

To write numeric data into an excel sheet, we need can use the writetable function. We have to use another function, the writematrix function.

writematrix(<data>, <filename>, <optional_values>)

The syntax is the same as the writetable just the datatype changes to double, float, or int.

Example 2:

Output:

In this code, we write the magic square matrix to an excel spreadsheet named new.xls. The following arguments define the sheet number and the starting cell where we want to write our matrix-formed data.

Writing a cell array (array of multiple data types) to an excel spreadsheet 

To write an array with both numeric and text data, we use the writecell() function. The syntax of the same is similar to writematrix and writetable however, the data type then changes to a cell array.

writecell(<data>, <filename>, <optional_values>)

In the following example, we will write a cell array to a new sheet in our new.xls spreadsheet. 

Example 3:

Output:

In this code, we are writing a 3×3 cell array to the spreadsheet in sheet 3 from a range of cells C1 to E2, this means that only as many elements as are specified in the range C1:E2.

This article is a quick tutorial on using the xlsread MATLAB command to import data from an Excel file into MATLAB. Specifically, you’ll learn to:

• Extract data from Excel in MATLAB
• Remove irrelevant content from your extract
• Import data from a specific sheet
• Select the Excel file to read
• Extract different formats

How to Extract Data from Excel in MATLAB

Xlsread Basic Syntax

Here’s the basic syntax to import data from Excel into MATLAB:

[numbers text textAndNumbers] = xlsread(excelFileName)

• numbers: numbers contained in your Excel file.
• text: text contained in your Excel file.
• textAndNumbers: text and numbers contained in your Excel file.

Xlsread MATLAB Example

First, let’s look at some details about how this works through an actual example. Let’s say I have the following Excel file named “excelFile.xlsx:”

Then, applying the previous basic syntax to read it, we get:

excelFileName = 'excelFile.xlsx';
[numbers text textAndNumbers] = xlsread(excelFileName);

So, let’s examine the outputs of the xlsread MATLAB command:

As you can see, the three outputs are not of the same data type:

• “numbers” is an array: this means that you can access the content of an element using parentheses: numbers(i)
• “text” is a cell array: this means that you can access the content of a cell using braces: text{i}
• “numbersAndText” is a cell array: this means that you can access the content of a cell using braces: numbersAndText{i}

Remove Irrelevant Content from Your Extract

• Notice that for the “numbers” variable, the first and last rows have been removed, and the text has been replaced by “NaN” value. You can get rid of the “NaN” values with the following:
  

  numbers = numbers(~isnan(numbers)); % delete numbers that are not "NaN"

  The “numbers” variable then becomes:
  

• The numbers contained in the “text” variable have been replaced by empty cells. You can get rid of the empty cells with the following:
  

  text = text(~cellfun('isempty', text)); % delete empty cells

  The “text” variable then becomes:
  

Import Data from a Specific Sheet

What If the Content Is in Another Sheet?

Let’s use the previous Excel file “excelFile.xlsx” with the content on a sheet named “Sheet1” (which is the default name of a sheet if you create an Excel file).
Moreover, if you add a sheet to the Excel file, the name of the sheet will be “Sheet2.” So, let’s do that and move the first sheet (with the previous content) to the right of the second sheet and save the file:

Then, we’ll apply the xlsread MATLAB command as we did previously:

excelFileName = 'excelFile.xlsx';
[numbers text textAndNumbers] = xlsread(excelFileName);

By default, xlsread will read the sheet located at the very left of the Excel file, namely “Sheet2.”

Since “Sheet2” is empty, it makes sense that the extracted content is empty. So, how do you read “Sheet1”?

Finding a Sheet

First, there are two ways to specify the sheet to read using the xlsread MATLAB command:

1. Using the number of the sheet:
   

   [numbers text textAndNumbers] = xlsread(excelFileName, sheetNumber);

   The number of the sheet is “2” here because we want to read the second sheet (counting from the left). So, giving the “sheetNumber” variable the value “1” is equivalent to not using the second argument of the xlsread MATLAB command. Here’s how to extract the desired sheet:

   sheetNumber = 2; % second sheet counting from the left
   excelFileName  = 'excelFile.xlsx';
   [numbers text textAndNumbers] = xlsread(excelFileName, sheetNumber);

2. Using the name of the sheet:
   

   [numbers text textAndNumbers] = xlsread(excelFileName, sheetName);

   The sheet name in that example is “Sheet1,” so you can use it as the second argument if you want to extract the second sheet:

   sheetName = 'Sheet1';
   excelFileName  = 'excelFile.xlsx';
   [numbers text textAndNumbers] = xlsread(excelFileName, sheetName);

In both cases, if the sheet number or the sheet name you’re referring to doesn’t exist, you’ll get the following error:

Specific Problems and Solutions

Ask the User to Select an Excel File

Using the uigetfile MATLAB command, you can ask the user to find and select the desired excel file to be read:

[fileName, pathName] = uigetfile({'*.xlsx';'*.xls'}, 'Choose an Excel file');

You can then use the “fileName” and the “pathName” (respectively the name of the selected file and its location) to read your Excel file.
There are 2 ways of doing that:

• Moving to the file’s location:
  

  [fileName, pathName] = uigetfile({'*.xlsx';'*.xls'}, 'Choose an Excel file');
  currentFolder = pwd; % save the current location
  cd(pathName)
  [numbers text textAndNumbers] = xlsread(fileName)
  cd(currentFolder);

  We use the pwd MATLAB command to save the current location from before, move to the Excel file’s location, perform the extraction, and move back to the initial location.

• Specifying the location:
  

  [fileName, pathName] = uigetfile({'*.xlsx';'*.xls'}, 'Choose an Excel file');
  fullFileExcelFile = fullfile(pathName, fileName); % create the path to the Excel file
  [numbers text textAndNumbers] = xlsread(fullFileExcelFile);

  fullfile creates the path by adding ‘/’ or ‘’ between the file name and the path name (you could do it yourself with something like [pathName ‘/’ fileName], but this can be a little bit trickier depending on whether you use a UNIX or Windows platform).

Be Careful About the Format of the Cells You’re Extracting

First, if the numbers contained in your Excel file are formatted as strings, you’ll get a cell array when extracting. For example, by adding a single quotation mark to the left of every number in the Excel file “excelFile.xlsx” that we’ve used previously, we are formatting them as strings:And if we import the data from the Excel file now, we get:

Since the numbers have been formatted as strings in the Excel file, there are no numbers anymore, the “numbers” variable is empty and the “text” and “textAndNumbers” variables have become identical.

The Empty Cell Issue

If you have empty cells in your Excel file before the first row, the xlsread MATLAB command will get rid of them. This is a problem if you want to write the content back to the Excel file (e.g. to modify a value) because you won’t be able to know where to write it.

Unfortunately, there is no easy way to get that information using xlsread. If you have this issue, you can refer to this article for a workaround: https://realtechnologytools.com/matlab-row-number/

Key takeaways:

• To read an Excel file, use:
  

  [numbers text textAndNumbers] = xlsread(excelFileName);

  • numbers: array of the numbers in the file, access an element using numbers(i)
  • text: cell array of the text in the file, access an element using text{i}
  • textAndNumbers: cell array of the text and numbers in the file, access an element using textAndNumbers{i}
• To remove irrelevant values from your extract, use:
  

  numbers = numbers(~isnan(numbers)); % delete numbers that are "NaN"
  text = text(~cellfun('isempty', text)); % delete empty cells

• To import a specific sheet in MATLAB, use:
  

  [numbers text textAndNumbers] = xlsread(excelFileName, sheetName); % use the sheet name
  [numbers text textAndNumbers] = xlsread(excelFileName, sheetNumber); % use the sheet number

• There are 2 ways to ask the user to select an Excel file and read it:
  1. By moving to the file’s location:
     

     [fileName, pathName] = uigetfile({'*.xlsx';'*.xls'}, 'Choose an Excel file');
     currentFolder = pwd; % save the current location
     cd(pathName)
     [numbers text textAndNumbers] = xlsread(fileName)
     cd(currentFolder);

  2. By specifying the location:
     

     [fileName, pathName] = uigetfile({'*.xlsx';'*.xls'}, 'Choose an Excel file');
     fullFileExcelFile = fullfile(pathName, fileName); % create the path to the Excel file
     [numbers text textAndNumbers] = xlsread(fullFileExcelFile);

• If the numbers in your Excel file are formatted as strings (e.g. using a single quotation mark at the left of a number in the Excel file), then they will be extracted in the “text” variable rather than in the “numbers” variable.

You can find more information about the xlsread MATLAB function in the MathWorks documation: https://fr.mathworks.com/help/matlab/ref/xlsread.html

If you want to learn more about the practical tips that helped me stop wasting time doing mindless work (such as working with Excel files and writing reports) I wrote a small reference book about it: