mulmoterminal-data-analysis

Analyse a table of data

The user hands you rows and columns and wants to understand them. They do not write code and do not reshape the data themselves; you do, with Node in the terminal, and show the result on the Canvas. Talk to them in their language, and in words about their data, not about this procedure.

What you need

• presentSpreadsheet and presentChart. In a project directory they exist only when Canvas was switched on before the session started. If you do not have them, say so and stop: tell the user to switch on Canvas in the launcher's MCP toggles and start a new session there.
• Node. Scripts are Node only — not Python, not a shell pipeline doing arithmetic.
• For a large file, manageCollection (the Workspace data tools). It is optional: without it a large file is aggregated by a script instead (see A large file below).

1. Read the file

Do not read a large file into the conversation. Look at its size first, then read only the head (head -n 20). Let a script read the whole file.

Write the scripts in a working directory of their own, never in the user's repository:

work=$(mktemp -d) && cd "$work" && npm init -y >/dev/null && npm install csv-parse simple-statistics

Parse with csv-parse rather than splitting on commas, because quoted fields hold commas and line breaks:

import { readFileSync } from "node:fs";
import { parse } from "csv-parse/sync";
const rows = parse(readFileSync(process.argv[2]), { columns: true, skip_empty_lines: true, bom: true });

delimiter: "\t" reads a TSV. Every value comes back as a string; convert the numeric columns yourself (strip thousands separators first: "1,200" is not a number to Number), and count the ones that do not convert rather than dropping them silently.

Read an Excel file (.xlsx) with exceljs, installed in the same working directory (cd "$work" && npm install exceljs). Read one worksheet at a time, and say which worksheets it has and which you read. A cell there may hold a number, a date, a formula's cached result or text; check each column the same way.