@tidyjs/tidy/dist/lib/expand.js

Tidy up your data with JavaScript, inspired by dplyr and the tidyverse

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

function expand(expandKeys) {
  const _expand = (items) => {
    const keyMap = makeKeyMap(expandKeys);
    const vectors = [];
    for (const key in keyMap) {
      const keyValue = keyMap[key];
      let values;
      if (typeof keyValue === "function") {
        values = keyValue(items);
      } else if (Array.isArray(keyValue)) {
        values = keyValue;
      } else {
        values = Array.from(new Set(items.map((d) => d[key])));
      }
      vectors.push(values.map((value) => ({[key]: value})));
    }
    return makeCombinations(vectors);
  };
  return _expand;
}
function makeCombinations(vectors) {
  function combine(accum, baseObj, remainingVectors) {
    if (!remainingVectors.length && baseObj != null) {
      accum.push(baseObj);
      return;
    }
    const vector = remainingVectors[0];
    const newRemainingArrays = remainingVectors.slice(1);
    for (const item of vector) {
      combine(accum, {...baseObj, ...item}, newRemainingArrays);
    }
  }
  const result = [];
  combine(result, null, vectors);
  return result;
}
function makeKeyMap(keys) {
  if (Array.isArray(keys)) {
    const keyMap = {};
    for (const key of keys) {
      keyMap[key] = key;
    }
    return keyMap;
  } else if (typeof keys === "object") {
    return keys;
  }
  return {[keys]: keys};
}

exports.expand = expand;
exports.makeKeyMap = makeKeyMap;
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