---
title: Spreadsheet Processing in Mathematica
sidebar_label: Mathematica
description: Build complex data pipelines in Mathematica Notebooks. Seamlessly create datasets with SheetJS. Leverage the Mathematica ecosystem to analyze data from Excel workbooks.
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---
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[Mathematica](https://mathematica.com) is a software system for mathematics and
scientific computing. It supports command-line tools and JavaScript extensions.
[SheetJS](https://sheetjs.com) 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 Mathematica. We'll explore how to run an external tool to generate CSV
data from opaque spreadsheets and parse the data from Mathematica.
:::note Tested Deployments
This demo was last tested by SheetJS users on 2023 November 04 in Mathematica 13.
:::
## Integration Details
The [SheetJS NodeJS module](/docs/getting-started/installation/nodejs) can be
loaded in NodeJS scripts, including scripts invoked using the `"NodeJS"` mode
of the `ExternalEvaluate`[^1] Mathematica function.
However, the current cross-platform recommendation involves a dedicated command
line tool that leverages SheetJS libraries to to perform spreadsheet processing.
### External Engines
The following diagram depicts the workbook waltz:
```mermaid
flowchart LR
subgraph `ExternalEvaluate`
file[(workbook\nfile)]
csvstr(CSV\nString)
end
data[(Dataset)]
file --> |NodeJS\nSheetJS Ops| csvstr
csvstr --> |ImportString\nMathematica| data
```
_Mathematica_
NodeJS can be activated from Mathematica using `RegisterExternalEvaluator`[^2].
Once activated, JavaScript code can be run using `ExternalEvaluate`[^3]. If the
NodeJS code returns CSV data, `ImportString`[^4] can generate a `Dataset`[^5].
_SheetJS_
For a file residing on the filesystem, the SheetJS `readFile` function[^6] can
generate a workbook object. The exact location can be determined by printing
`require("process").cwd()`[^7] in `ExternalEvaluate`:
```mathematica
In[1]:= ExternalEvaluate["NodeJS", "require('process').cwd()"]
Out[1]= "C:\Users\Me\Documents"
```
After pulling the first worksheet[^8], the SheetJS `sheet_to_csv` function[^9]
generates a CSV string.
_Complete Function_
The following function reads a file, parses the first worksheet and returns a
Dataset object assuming one header row.
```mathematica title="Complete Function"
(* Import file stored in the Documents folder (e.g. C:\Users\Me\Documents) *)
SheetJSImportFileEE[filename_]:=Module[{csv}, (
(* This was required in local testing *)
RegisterExternalEvaluator["NodeJS","/usr/local/bin/node"];
(* Generate CSV from first sheet *)
csv:=ExternalEvaluate["NodeJS", StringJoin[
(* module installed in home directory *)
"var XLSX = require('xlsx');",
(* read specified filename *)
"var wb = XLSX.readFile('",filename,"');",
(* grab first worksheet *)
"var ws = wb.Sheets[wb.SheetNames[0]];",
(* convert to CSV *)
"XLSX.utils.sheet_to_csv(ws)"
]];
(* Parse CSV into a dataset *)
Return[ImportString[csv, "Dataset", "HeaderLines"->1]];
)]
```
```mathematica title="Complete Function"
(* Import file stored in the Documents folder (e.g. C:\Users\Me\Documents) *)
SheetJSImportFileEE[filename_]:=Module[{csv}, (
(* This was required in local testing *)
RegisterExternalEvaluator["NodeJS","C:\\Program Files\\nodejs\\node.exe"];
(* Generate CSV from first sheet *)
csv:=ExternalEvaluate["NodeJS", StringJoin[
(* module installed in home directory *)
"var XLSX = require('xlsx');",
(* read specified filename *)
"var wb = XLSX.readFile('",filename,"');",
(* grab first worksheet *)
"var ws = wb.Sheets[wb.SheetNames[0]];",
(* convert to CSV *)
"XLSX.utils.sheet_to_csv(ws)"
]];
(* Parse CSV into a dataset *)
Return[ImportString[csv, "Dataset", "HeaderLines"->1]];
)]
```
How to run the example (click to hide)
:::note Tested Deployments
This example was last tested on 2023 November 04 with Mathematica 13.3.
:::
0) Install NodeJS. When the demo was tested, version `20.9.0` was installed.
1) Install dependencies in the Home folder (`~` or `$HOME` or `%HOMEPATH%`):
{`\
npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz zeromq@6.0.0-beta.17`}
2) Open a new Mathematica Notebook and register NodeJS. When the example was
tested in Windows, the commands were:
```mathematica
RegisterExternalEvaluator["NodeJS","/usr/local/bin/node"]
FindExternalEvaluators["NodeJS"]
```
```mathematica
RegisterExternalEvaluator["NodeJS","C:\\Program Files\\nodejs\\node.exe"]
FindExternalEvaluators["NodeJS"]
```
The second argument to `RegisterExternalEvaluator` should be the path to the
`node` or `node.exe` binary.
If NodeJS is registered, the value in the "Registered" column will be "True".
4) To determine the base folder, run `require("process").cwd()` from NodeJS:
```mathematica
ExternalEvaluate["NodeJS", "require('process').cwd()"]
```
5) Download [`pres.numbers`](https://sheetjs.com/pres.numbers) and move the file
to the base folder as shown in the previous step.
6) Copy and evaluate the "Complete Function" in the previous codeblock.
7) Run the function and confirm the result is a proper Dataset:
```mathematica
SheetJSImportFileEE["pres.numbers"]
```
