docs.sheetjs.com/docz/docs/03-demos/32-extensions/11-matlab.md

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Modern Spreadsheets in MATLAB	MATLAB	Build complex data pipelines in MATLAB M-Files. Seamlessly create MATLAB tables with SheetJS. Leverage the MATLAB toolbox ecosystem to analyze data from Excel workbooks.	demos/cloud/index	demos/bigdata/index

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MATLAB is a numeric computing platform. It has a native table type with limited support for spreadsheets.

SheetJS is a JavaScript library for reading and writing data from spreadsheets.

This demo uses SheetJS to pull data from a spreadsheet for further analysis within MATLAB. We'll explore how to run an external tool to convert complex spreadsheets into simple XLSX files for MATLAB.

:::note

This demo was last tested by SheetJS users on 2023 September 12 in MATLAB R2023a.

:::

:::info pass

MATLAB has limited support for processing spreadsheets through readtable¹ and writetable². At the time of writing, it lacked support for XLSB, NUMBERS, and other common spreadsheet formats.

SheetJS libraries help fill the gap by normalizing spreadsheets to a form that MATLAB can understand.

:::

Integration Details

:::note pass

MATLAB does not currently provide a way to parse a CSV string or a character array representing file data. readtable, writetable, csvread, and csvwrite work with the file system directly. strread and textscan are designed specifically for reading numbers.

:::

The current recommendation involves a dedicated command-line tool that leverages SheetJS libraries to to perform spreadsheet processing.

The SheetJS NodeJS module can be loaded in NodeJS scripts and bundled in standalone command-line tools.

Command-Line Tools

The "Command-Line Tools" demo creates xlsx-cli, a command-line tool that reads a spreadsheet file and generates output. The examples in the "NodeJS" section are able to generate XLSX spreadsheets using the --xlsx command line flag:

$ xlsx-cli --xlsx ./pres.numbers ## generates pres.numbers.xlsx

:::note pass

The command-line tool supports a number of formats including XLSB (--xlsb).

:::

The tools pair the SheetJS readFile³ and writeFile⁴ methods to read data from arbitrary spreadsheet files and convert to XLSX:

const XLSX = require("xlsx"); // load the SheetJS library
const wb = XLSX.readFile("input.xlsb"); // read input.xlsb
XLSX.writeFile(wb, "output.xlsx"); // export to output.xlsx

MATLAB commands

The MATLAB system command⁵ can run command-line tools in M-files. For example, if the xlsx-cli tool is placed in the workspace folder and the test file pres.numbers is in the Downloads folder, the following command generates the XLSX file pres.numbers.xlsx :

% generate ~/Downloads/pres.numbers.xlsx from ~/Downloads/pres.numbers
system("./xlsx-cli --xlsx ~/Downloads/pres.numbers");

:::note pass

In an interactive session, the exclamation point operator !⁶ can be used:

% generate ~/Downloads/pres.numbers.xlsx from ~/Downloads/pres.numbers
!./xlsx-cli --xlsx ~/Downloads/pres.numbers

:::

Reading Files

Starting from an arbitrary spreadsheet, xlsx-cli can generate a XLSX workbook. Once the workbook is written, the XLSX file can be parsed with readtable:

% `filename` points to the file to be parsed
filename = "~/Downloads/pres.numbers";
% generate filename+".xlsx"
system("./xlsx-cli --xlsx " + filename)
% read using `readtable`
tbl = readtable(filename + ".xlsx");

The following diagram depicts the workbook waltz:

flowchart LR
  subgraph MATLAB `system` invocation
    file[(workbook\nunknown type)]
    xlsx(XLSX\nNormalized Data)
  end
  data[(table)]
  file --> |`xlsx-cli`\nSheetJS| xlsx
  xlsx --> |`readtable`\nMATLAB| data

Write Files

Starting from an MATLAB table, writetable can generate a XLSX workbook. Once the workbook is written, xlsx-cli can translate to NUMBERS or other formats:

% tbl is the table
tbl = table({"Sheet";"JS"}, [72;62], 'VariableNames', ["Name", "Index"])
% `filename` points to the file to be written
filename = "~/Downloads/sorted.xlsx";
% write using `writetable`
writetable(tbl, filename);
% generate filename+".xlsb"
system("./xlsx-cli --xlsb " + filename);

The following diagram depicts the workbook waltz:

flowchart LR
  subgraph MATLAB `system` invocation
    file[(XLSB\nworkbook)]
    xlsx(XLSX\nNormalized Data)
  end
  data[(table)]
  data --> |`writetable`\nMATLAB| xlsx
  xlsx --> |`xlsx-cli`\nSheetJS| file

Complete Demo

:::info pass

This demo was tested in macOS. The path names will differ in other platforms.

:::

This demo uses the pres.numbers test file. There are 3 parts to the demo:

A) "Import": SheetJS tooling will read the test file and generate a clean XLSX file. MATLAB will read the file using readtable.

B) "Process": Using sortrows, MATLAB will reverse the table order.

C) "Export": The modified table will be exported to XLSX using writetable. SheetJS tooling will convert the file to XLSB.

flowchart LR
  ifile[(NUMBERS)]
  ixlsx(XLSX)
  ofile[(XLSB)]
  oxlsx(XLSX)
  data[(table)]
  ifile --> |`xlsx-cli`\nSheetJS| ixlsx
  ixlsx --> |`readtable`\nMATLAB| data
  data -.-> |Data Processing| data
  data --> |`writetable`\nMATLAB| oxlsx
  oxlsx --> |`xlsx-cli`\nSheetJS| ofile

1. Create the standalone xlsx-cli binary⁷:

{\ cd /tmp npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz exit-on-epipe commander@2 curl -LO https://docs.sheetjs.com/cli/xlsx-cli.js npx nexe -t 14.15.3 xlsx-cli.js}

2. Move the generated xlsx-cli to the MATLAB workspace folder. On macOS, this folder is typically ~/Documents/MATLAB/:

mkdir -p ~/Documents/MATLAB/
mv xlsx-cli ~/Documents/MATLAB/

3. Download https://sheetjs.com/pres.numbers and save to Downloads folder:

cd ~/Downloads/
curl -LO https://sheetjs.com/pres.numbers

4. Save the following to SheetJSMATLAB.m in the workspace folder:

% Import data from NUMBERS file
system("./xlsx-cli --xlsx ~/Downloads/pres.numbers");
tbl = readtable("~/Downloads/pres.numbers.xlsx");
% Process data (reverse sort)
sorted = sortrows(tbl,"Index", "descend");
% Export data to XLSB workbook
writetable(sorted,"~/Downloads/sorted.xlsx");
system("./xlsx-cli --xlsb ~/Downloads/sorted.xlsx");

5. In a MATLAB desktop session, run the SheetJSMATLAB command:

>> SheetJSMATLAB

It will create the file sorted.xlsx.xlsb in the ~/Downloads folder. Open the file and confirm that the table is sorted by Index in descending order:

Name           Index
Joseph Biden      46
Donald Trump      45
Barack Obama      44
GeorgeW Bush      43
Bill Clinton      42

:::tip pass

If the matlab command is available on the system PATH, the "headless" version of the command is:

cd ~/Documents/MATLAB
matlab -batch SheetJSMATLAB

:::

---

1. See readtable in the MATLAB documentation. ↩︎

2. See writetable in the MATLAB documentation. ↩︎

3. See readFile in "Reading Files" ↩︎

4. See writeFile in "Writing Files" ↩︎

5. See system in the MATLAB documentation. ↩︎

6. See "MATLAB Operators and Special Characters in the MATLAB documentation. ↩︎

7. See "Command-line Tools" for more details. ↩︎