cheap-pandas/lib.js

Not a good pandas library to use

exports.toFixed4Digit = (item) => {
  return item.toFixed(4).replace(/(\.0+$)|(0+$)/g, "");
};
exports.takeNSpace = (item = "", num) => {
  if (typeof item === "number") item = exports.toFixed4Digit(item);
  if (item.length + 2 > num) {
    item = item.substring(0, num - 2);
  }
  return `|${" ".repeat(
    Math.floor((num - item.length) / 2)
  )}${item}${" ".repeat(Math.ceil((num - item.length) / 2))}`;
};

exports.sqrt = (a) => Math.sqrt(a);

exports.sq = (a) => Math.pow(a, 2);

exports.pow = (a, b) => Math.pow(a, b);

exports.getRange = (a, b) => [a - b, a + b];

exports.mean = (arr) => arr.reduce((prev, curr) => prev + curr, 0) / arr.length;

exports.variance = (arr) => {
  let mean = exports.mean(arr);
  let cum = 0;
  for (let i = 0; i < arr.length; i++) {
    cum += exports.sq(arr[i] - mean);
  }
  return cum / (arr.length - 1);
};

exports.std = (arr) => Math.sqrt(exports.variance(arr));
exports.div = (a, b, fn) => {
  if (typeof a === "number" && typeof b === "number") {
    return a / b;
  }

  if (Array.isArray(a) && Array.isArray(b)) {
    if (a.length !== b.length) throw new Error("Their length must be the same");
    let divided_array = [];

    if (fn) {
      for (let i = 0; i < a.length; i++) {
        divided_array[i] = fn(a[i] / b[i]);
      }
    } else {
      for (let i = 0; i < a.length; i++) {
        divided_array[i] = a[i] / b[i];
      }
    }

    return divided_array;
  }
  return null;
};

exports.combination = (n, k) => {
  let mul = 1;
  for (let i = n; i > k; i--) {
    mul *= i;
  }
  let other = n - k;
  for (let i = other; i >= 1; i--) {
    mul /= i;
  }
  return mul;
};

exports.binomial = (n, t, p) =>
  exports.combination(n, t) * Math.pow(p, t) * Math.pow(1 - p, n - t);

exports.log = (base, argument) => {
  if (typeof argument === "undefined") {
    return Math.log(base);
  }
  return Math.log(argument) / Math.log(base);
};

exports.sum = (arr) => {
  return arr.reduce((prev, curr) => prev + curr, 0);
};

exports.sub = (a, b, fn) => {
  if (typeof a === "number" && typeof b === "number") {
    return a - b;
  }

  if (Array.isArray(a) && Array.isArray(b)) {
    if (a.length !== b.length) throw new Error("Their length must be the same");
    let subtracted_array = [];

    if (fn) {
      for (let i = 0; i < a.length; i++) {
        subtracted_array[i] = fn(a[i] - b[i]);
      }
    } else {
      for (let i = 0; i < a.length; i++) {
        subtracted_array[i] = a[i] - b[i];
      }
    }

    return subtracted_array;
  }
  return null;
};