A way to handle nested objects

[graemebruce]

When bringing in json data using loadData or loadGeoData, something is needed to handle nested objects. Example dataset:
https://dd.weather.gc.ca/hurricanes/20240802T1500Z_MSC_Hurricane_FOUR.json

Column "metobject"

[nshiab]

You can access the values in nested objects by casting them to JSON.

Create a new folder and run npx simple-data-analysis, copy-paste the code below into your index.js or index.ts, then run npm run sda and you should see a new column classification at the end of the table.

The casting to JSON happens on line 24.

import { SimpleDB } from "simple-data-analysis";
import { prettyDuration } from "journalism";

const start = Date.now();

// We set a maximum width to the string columns to keep it readable.
const sdb = new SimpleDB({ nbCharactersToLog: 50 });

const table = sdb.newTable();

// We cache so we don't fetch everytime while working on the file.
await table.cache(async () => {
  await table.loadGeoData(
    "https://dd.weather.gc.ca/hurricanes/20240802T1500Z_MSC_Hurricane_FOUR.json"
  );
  // Some geometries are null. We exclude them.
  await table.filter(`geom NOT NULL`);
});

// We extract the classification after casting to JSON.
await table.addColumn(
  `classification`,
  "string",
  `CAST(metobject AS JSON).classification`
);
// We clean up the extra quotes around classifications.
await table.replace("classification", { '"': "" });

await table.logTable();

prettyDuration(start, { log: true, prefix: "\nDone in " });