freeCodeCamp/step-125.md at 2fbafda16721fd83a2f700a24a129b913691619c

SomeDer 2fbafda167 feat: functional programming spreadsheet (#36873 )

* Add meta.json for spreadsheet

* Add spreadsheet files

* Close code tags for tests in 2 files

* Add solution section

* Add index file

* Add javascript-spreadsheet to stringifier

* Move index to step

* Rename steps in meta.json

* Rename step numbers in files

* Add index file to proper location

* Remove inappropriate files from spreadsheet dir

* Fix typo in first step

* Fix test sections

* Rename files to correct step

* Fix broken tests

* Add newline between sections

* Change challengeType from 1 to 0

* Add missng ) in step-079.md

* test -> tests in step-079

* Simplify test in step-103

* Fix step-137 test

* Remove last step

* Added solutions and adjusted some tests

* Fix some challenges

* Remove wrong spaces

* Fix more tests

* Add missing semicolon

* Fix more tests

* Fix type: lastttwo

* Fix all remaining tests

2020-09-16 11:53:59 +05:30

8.0 KiB

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id, title, challengeType, isBeta

id	title	challengeType	isBeta
5d792539ec758d45a6900173	Step 125	0	true

Description

The length property returns the length of an array. Use this property with the sum function to define an average function. As with sum, add this function to both the global scope and to spreadsheetFunctions.

Instructions

Tests

tests:
  - text: See description above for instructions.
    testString: assert(average([1, 5, 12]) === 6 && spreadsheetFunctions.average([1, 20, 3, 8]) === 8);

Challenge Seed

<script>

const infixToFunction = {
  "+": (x, y) => x + y,
  "-": (x, y) => x - y,
  "*": (x, y) => x * y,
  "/": (x, y) => x / y
};

const infixEval = (str, regex) =>
  str.replace(regex, (_, arg1, fn, arg2) =>
    infixToFunction[fn](parseFloat(arg1), parseFloat(arg2))
  );

const highPrecedence = str => {
  const regex = /([0-9.]+)([*\/])([0-9.]+)/;
  const str2 = infixEval(str, regex);
  return str === str2 ? str : highPrecedence(str2);
};

const isEven = num => num % 2 === 0;
const sum = nums => nums.reduce((a, x) => a + x);

const spreadsheetFunctions = {
  "": x => x,
  random: ([x, y]) => Math.floor(Math.random() * y + x),
  increment: nums => nums.map(x => x + 1),
  firsttwo: arr => arr.slice(0, 2),
  lasttwo: arr => arr.slice(-2),
  even: nums => nums.filter(isEven),
  sum,
  has2: arr => arr.includes(2),
  nodups: arr => arr.reduce((a, x) => a.includes(x) ? a : a.concat(x), [])
};



const applyFn = str => {
  const noHigh = highPrecedence(str);
  const infix = /([0-9.]+)([+-])([0-9.]+)/;
  const str2 = infixEval(noHigh, infix);
  const regex = /([a-z]*)\(([0-9., ]*)\)(?!.*\()/i;
  const toNumberList = args => args.split(",").map(parseFloat);
  const applyFunction = (fn, args) =>
    spreadsheetFunctions[fn.toLowerCase()](toNumberList(args));
  return str2.replace(
    regex,
    (match, fn, args) =>
      spreadsheetFunctions.hasOwnProperty(fn.toLowerCase()) ? applyFunction(fn, args) : match
  );
};

const range = (start, end) =>
  start > end ? [] : [start].concat(range(start + 1, end));

const charRange = (start, end) =>
  range(start.charCodeAt(0), end.charCodeAt(0)).map(x =>
    String.fromCharCode(x)
  );

const evalFormula = (x, cells) => {
  const idToText = id => cells.find(cell => cell.id === id).value;
  const rangeRegex = /([A-J])([1-9][0-9]?):([A-J])([1-9][0-9]?)/gi;
  const rangeFromString = (n1, n2) => range(parseInt(n1), parseInt(n2));
  const elemValue = n => c => idToText(c + n);
  const addChars = c1 => c2 => n => charRange(c1, c2).map(elemValue(n));
  const varRangeExpanded = x.replace(rangeRegex, (_, c1, n1, c2, n2) =>
    rangeFromString(n1, n2).map(addChars(c1)(c2))
  );
  const varRegex = /[A-J][1-9][0-9]?/gi;
  const varExpanded = varRangeExpanded.replace(
    varRegex,
    match => idToText(match.toUpperCase())
  );
  const functionExpanded = applyFn(varExpanded);
  return functionExpanded === x
    ? functionExpanded
    : evalFormula(functionExpanded, cells);
};

window.onload = () => {
  const container = document.getElementById("container");
  const createLabel = name => {
    const label = document.createElement("div");
    label.className = "label";
    label.textContent = name;
    container.appendChild(label);
  };
  const letters = charRange("A", "J");
  letters.forEach(createLabel);
  range(1, 99).forEach(x => {
    createLabel(x);
    letters.forEach(y => {
      const input = document.createElement("input");
      input.type = "text";
      input.id = y + x;
      input.onchange = update;
      container.appendChild(input);
    });
  });
};

const update = event => {
  const element = event.target;
  const value = element.value.replace(/\s/g, "");
  if (!value.includes(element.id) && value[0] === "=") {
    element.value = evalFormula(
      value.slice(1),
      Array.from(document.getElementById("container").children)
    );
  }
};
</script>

Before Test

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Spreadsheet</title>
  <style>
    #container {
      display: grid;
      grid-template-columns: 50px repeat(10, 200px);
      grid-template-rows: repeat(11, 30px);
    }
    .label {
      background-color: lightgray;
      text-align: center;
      vertical-align: middle;
      line-height: 30px;
    }
  </style>
</head>
<body>
<div id="container">
  <div></div>
</div>

After Test

</body>
</html>

Solution

<script>
const infixToFunction = {
  "+": (x, y) => x + y,
  "-": (x, y) => x - y,
  "*": (x, y) => x * y,
  "/": (x, y) => x / y
};

const infixEval = (str, regex) =>
  str.replace(regex, (_, arg1, fn, arg2) =>
    infixToFunction[fn](parseFloat(arg1), parseFloat(arg2))
  );

const highPrecedence = str => {
  const regex = /([0-9.]+)([*\/])([0-9.]+)/;
  const str2 = infixEval(str, regex);
  return str === str2 ? str : highPrecedence(str2);
};

const isEven = num => num % 2 === 0;
const sum = nums => nums.reduce((a, x) => a + x);
const average = nums => sum(nums) / nums.length;

const spreadsheetFunctions = {
  "": x => x,
  random: ([x, y]) => Math.floor(Math.random() * y + x),
  increment: nums => nums.map(x => x + 1),
  firsttwo: arr => arr.slice(0, 2),
  lasttwo: arr => arr.slice(-2),
  even: nums => nums.filter(isEven),
  sum,
  average,
  has2: arr => arr.includes(2),
  nodups: arr => arr.reduce((a, x) => a.includes(x) ? a : a.concat(x), [])
};



const applyFn = str => {
  const noHigh = highPrecedence(str);
  const infix = /([0-9.]+)([+-])([0-9.]+)/;
  const str2 = infixEval(noHigh, infix);
  const regex = /([a-z]*)\(([0-9., ]*)\)(?!.*\()/i;
  const toNumberList = args => args.split(",").map(parseFloat);
  const applyFunction = (fn, args) =>
    spreadsheetFunctions[fn.toLowerCase()](toNumberList(args));
  return str2.replace(
    regex,
    (match, fn, args) =>
      spreadsheetFunctions.hasOwnProperty(fn.toLowerCase()) ? applyFunction(fn, args) : match
  );
};

const range = (start, end) =>
  start > end ? [] : [start].concat(range(start + 1, end));

const charRange = (start, end) =>
  range(start.charCodeAt(0), end.charCodeAt(0)).map(x =>
    String.fromCharCode(x)
  );

const evalFormula = (x, cells) => {
  const idToText = id => cells.find(cell => cell.id === id).value;
  const rangeRegex = /([A-J])([1-9][0-9]?):([A-J])([1-9][0-9]?)/gi;
  const rangeFromString = (n1, n2) => range(parseInt(n1), parseInt(n2));
  const elemValue = n => c => idToText(c + n);
  const addChars = c1 => c2 => n => charRange(c1, c2).map(elemValue(n));
  const varRangeExpanded = x.replace(rangeRegex, (_, c1, n1, c2, n2) =>
    rangeFromString(n1, n2).map(addChars(c1)(c2))
  );
  const varRegex = /[A-J][1-9][0-9]?/gi;
  const varExpanded = varRangeExpanded.replace(
    varRegex,
    match => idToText(match.toUpperCase())
  );
  const functionExpanded = applyFn(varExpanded);
  return functionExpanded === x
    ? functionExpanded
    : evalFormula(functionExpanded, cells);
};

window.onload = () => {
  const container = document.getElementById("container");
  const createLabel = name => {
    const label = document.createElement("div");
    label.className = "label";
    label.textContent = name;
    container.appendChild(label);
  };
  const letters = charRange("A", "J");
  letters.forEach(createLabel);
  range(1, 99).forEach(x => {
    createLabel(x);
    letters.forEach(y => {
      const input = document.createElement("input");
      input.type = "text";
      input.id = y + x;
      input.onchange = update;
      container.appendChild(input);
    });
  });
};

const update = event => {
  const element = event.target;
  const value = element.value.replace(/\s/g, "");
  if (!value.includes(element.id) && value[0] === "=") {
    element.value = evalFormula(
      value.slice(1),
      Array.from(document.getElementById("container").children)
    );
  }
};
</script>

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