node-seasonal

A simple Node.js wrapper for X-13-ARIMA-SEATS, the seasonal adjustment software by the U.S. Census Bureau

Installation and usage

Install:

npm install --save node-seasonal

Use:

const seasonal = require('node-seasonal');

// Your input data must be an array of objects with a field for the date and at least one field that has values.
const input_data = [
  {
    month: "1998-01", // Dates must be formatted YYYY-MM
    shoe_sales: 100343,
    shirt_sales: 35991
  },
  // { ... } etc etc
];

// Specify the names of the fields that hold your date and value(s)
const options = {
  date_field: "month",
  value_fields: ["shoe_sales", "shirt_sales"], // The values in the fields listed here will be seasonally adjusted
  table_ids: ["d11"], // d11 just means standard seasonal adjustment (see below)
  output_dir: `${__dirname}/output`, // WHere to save x13 files (they are deleted if this is left empty)
  log: true // Whether to log output of x13 command
};

const adjusted_data = seasonal.adjust(input_data, options);

The above will auto-adjust the input data and append the adjusted numbers to it. The output will include the original data, with new fields for the adjusted numbers which include the requested table IDs. That is, in the example above, adjusted_data would look like this:

[
  {
    month: "1998-01",
    shoe_sales: 100343,
    shirt_sales: 35991,
    shoe_sales_d11: 90443, // seasonally-adjusted value
    shirt_sales_d11: 38002 // seasonally-adjusted value
  },
  // { ... } etc etc
]

Each valid table ID specified in the options will append a new field for each value field specified.

Options

Required properties:

date_field (String) Date format must be YYYY-MM; (seasonal.adjust() only supports monthly adjustments)

value_fields (Array of strings) Should include all fields in input data that should be seasonally adjusted

table_ids (Array of strings) Refer to the x13ashtml reference manual for a listing of codes (d11 is final seasonally adjusted numbers)

Optional properties:

output_dir (String) Where to output x13ashtml files. If empty or null, output files are deleted.

log (Boolean) Whether to log output of x13ashtml command, which is useful for debugging. (Default is false.)

Use a custom .spc file

seasonal.custom({
  input_file_path: `${__dirname}/input_filename`, // Required
  log: true // Optional (default is false)
});

This simply runs a .spc file you create on your own and saves the x13ashtml output files. The files will be saved to the same directory where the input spec file is. Refer to the x13ashtml reference manual for the specifications of the input files.