austrian-cpi/src/api.js

Query and merge Austrian CPI time series data for economic modeling

import { austrianCPI } from "../austrianCPI.js";
import { parsePeriod, normalizeDate } from "./cpiUtils.js";

/**
 * Query CPI
 * @param {string} start - e.g. '2022-01' or '2022'
 * @param {string} end - e.g. '2023-12' or '2023'
 * @param {{ frequency?: 'monthly' | 'yearly', series?: string[] }} options
 * @returns {Array<Object>}
 */
function queryCPI(start, end, options) {
  options = options || {};
  const frequency = options.frequency || "monthly";
  const series = Array.isArray(options.series) ? options.series : [];

  const startParts = start.split("-");
  const endParts = end.split("-");
  const startYear = parseInt(startParts[0], 10);
  const startMonth = startParts.length > 1 ? parseInt(startParts[1], 10) : 1;
  const endYear = parseInt(endParts[0], 10);
  const endMonth = endParts.length > 1 ? parseInt(endParts[1], 10) : 12;

  const min = startYear * 100 + startMonth;
  const max = endYear * 100 + endMonth;

  const result = [];

  for (let i = 0; i < austrianCPI.length; i++) {
    const row = austrianCPI[i];
    const parsed = parsePeriod(row);
    if (!parsed || parsed.type !== frequency) continue;

    const y = parsed.year;
    const m = parsed.month || 1;
    const dateKey = `${y}-${m.toString().padStart(2, "0")}`;

    if (dateKey < start || dateKey > end) continue;

    const values = {};
    for (let j = 0; j < series.length; j++) {
      const key = series[j];
      let val = row[key];
      if (
        val === "None" ||
        val === undefined ||
        val === null ||
        typeof val === "object"
      ) {
        values[key] = null;
      } else if (typeof val === "string") {
        values[key] = parseFloat(val.replace(",", "."));
      } else {
        values[key] = val;
      }
    }

    result.push(Object.assign({ date: dateKey }, values));
  }

  return result;
}

/**
 * Convert to CSV
 * @param {Array<Object>} data
 * @returns {string}
 */
function exportToCSV(data) {
  if (!Array.isArray(data) || data.length === 0) return "";

  const keys = ["date"].concat(
    Object.keys(data[0]).filter((k) => k !== "date"),
  );
  const header = keys.join(",");
  const rows = data.map((row) =>
    keys
      .map((k) => {
        const val = row[k];
        return val !== undefined && val !== null ? val : "";
      })
      .join(","),
  );

  return [header].concat(rows).join("\n");
}

/**
 * Merge CPI into other dataset by date key
 * @param {Array<Object>} cpiData
 * @param {Array<Object>} otherData
 * @returns {Array<Object>}
 */
function mergeWith(cpiData, otherData) {
  const cpiMap = {};
  const allKeys = new Set();

  for (let i = 0; i < cpiData.length; i++) {
    const row = cpiData[i];
    const normDate = normalizeDate(row.date);
    cpiMap[normDate] = row;

    for (const key in row) {
      if (key !== "date") allKeys.add(key);
    }
  }

  return otherData.map((row) => {
    const normDate = normalizeDate(row.date);
    const match = cpiMap[normDate];
    const merged = { ...row };

    allKeys.forEach((key) => {
      let val = match && key in match ? match[key] : null;

      // Warn and sanitize
      if (val !== null && typeof val === "object") {
        console.warn("Unexpected object for key:", key, "on date:", normDate);
        val = null;
      }

      merged[key] = val;
    });

    return merged;
  });
}

export { queryCPI, mergeWith, exportToCSV };