Transform numbers to words in lakh / crore system

javascript numbers

I'm writing some code that converts a given number into words, here's what I have got after googling. But I think it's a bit too long for such a simple task. Two Regular Expressions and two for loops, I want something simpler.

I am trying to achieve this in as few lines of code as possible. here's what I've come up with so far:

Any suggestions?

var th = ['','thousand','million', 'billion','trillion'];
var dg = ['zero','one','two','three','four', 'five','six','seven','eight','nine'];
 var tn = ['ten','eleven','twelve','thirteen', 'fourteen','fifteen','sixteen', 'seventeen','eighteen','nineteen'];
 var tw = ['twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];
 
function toWords(s) {
    s = s.toString();
    s = s.replace(/[\, ]/g,'');
    if (s != parseFloat(s)) return 'not a number';
    var x = s.indexOf('.');
    if (x == -1)
        x = s.length;
    if (x > 15)
        return 'too big';
    var n = s.split(''); 
    var str = '';
    var sk = 0;
    for (var i=0;   i < x;  i++) {
        if ((x-i)%3==2) { 
            if (n[i] == '1') {
                str += tn[Number(n[i+1])] + ' ';
                i++;
                sk=1;
            } else if (n[i]!=0) {
                str += tw[n[i]-2] + ' ';
                sk=1;
            }
        } else if (n[i]!=0) { // 0235
            str += dg[n[i]] +' ';
            if ((x-i)%3==0) str += 'hundred ';
            sk=1;
        }
        if ((x-i)%3==1) {
            if (sk)
                str += th[(x-i-1)/3] + ' ';
            sk=0;
        }
    }
    
    if (x != s.length) {
        var y = s.length;
        str += 'point ';
        for (var i=x+1; i<y; i++)
            str += dg[n[i]] +' ';
    }
    return str.replace(/\s+/g,' ');
}

Also, the above code converts to the English numbering system like Million/Billion, I need the South Asian numbering system, like in Lakhs and Crores.


Solution 1:

Update: Looks like this is more useful than I thought. I've just published this on npm. https://www.npmjs.com/package/num-words

Here's a shorter code. with one RegEx and no loops. converts as you wanted, in south asian numbering system

var a = ['','one ','two ','three ','four ', 'five ','six ','seven ','eight ','nine ','ten ','eleven ','twelve ','thirteen ','fourteen ','fifteen ','sixteen ','seventeen ','eighteen ','nineteen '];
var b = ['', '', 'twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];

function inWords (num) {
    if ((num = num.toString()).length > 9) return 'overflow';
    n = ('000000000' + num).substr(-9).match(/^(\d{2})(\d{2})(\d{2})(\d{1})(\d{2})$/);
    if (!n) return; var str = '';
    str += (n[1] != 0) ? (a[Number(n[1])] || b[n[1][0]] + ' ' + a[n[1][1]]) + 'crore ' : '';
    str += (n[2] != 0) ? (a[Number(n[2])] || b[n[2][0]] + ' ' + a[n[2][1]]) + 'lakh ' : '';
    str += (n[3] != 0) ? (a[Number(n[3])] || b[n[3][0]] + ' ' + a[n[3][1]]) + 'thousand ' : '';
    str += (n[4] != 0) ? (a[Number(n[4])] || b[n[4][0]] + ' ' + a[n[4][1]]) + 'hundred ' : '';
    str += (n[5] != 0) ? ((str != '') ? 'and ' : '') + (a[Number(n[5])] || b[n[5][0]] + ' ' + a[n[5][1]]) + 'only ' : '';
    return str;
}

document.getElementById('number').onkeyup = function () {
    document.getElementById('words').innerHTML = inWords(document.getElementById('number').value);
};
<span id="words"></span>
<input id="number" type="text" />

The only limitation is, you can convert maximum of 9 digits, which I think is more than sufficient in most cases..

Solution 2:

"Deceptively simple task." – Potatoswatter

Indeed. There's many little devils hanging out in the details of this problem. It was very fun to solve tho.

EDIT: This update takes a much more compositional approach. Previously there was one big function which wrapped a couple other proprietary functions. Instead, this time we define generic reusable functions which could be used for many varieties of tasks. More about those after we take a look at numToWords itself …

// numToWords :: (Number a, String a) => a -> String
let numToWords = n => {
  let a = [
    '', 'one', 'two', 'three', 'four',
    'five', 'six', 'seven', 'eight', 'nine',
    'ten', 'eleven', 'twelve', 'thirteen', 'fourteen',
    'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen'
  ];
  let b = [
    '', '', 'twenty', 'thirty', 'forty',
    'fifty', 'sixty', 'seventy', 'eighty', 'ninety'
  ];
  let g = [
    '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion',
    'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion'
  ];
  // this part is really nasty still
  // it might edit this again later to show how Monoids could fix this up
  let makeGroup = ([ones,tens,huns]) => {
    return [
      num(huns) === 0 ? '' : a[huns] + ' hundred ',
      num(ones) === 0 ? b[tens] : b[tens] && b[tens] + '-' || '',
      a[tens+ones] || a[ones]
    ].join('');
  };
  // "thousands" constructor; no real good names for this, i guess
  let thousand = (group,i) => group === '' ? group : `${group} ${g[i]}`;
  // execute !
  if (typeof n === 'number') return numToWords(String(n));
  if (n === '0')             return 'zero';
  return comp (chunk(3)) (reverse) (arr(n))
    .map(makeGroup)
    .map(thousand)
    .filter(comp(not)(isEmpty))
    .reverse()
    .join(' ');
};

Here are the dependencies:

You'll notice these require next to no documentation because their intents are immediately clear. chunk might be the only one that takes a moment to digest, but it's really not too bad. Plus the function name gives us a pretty good indication what it does, and it's probably a function we've encountered before.

const arr = x => Array.from(x);
const num = x => Number(x) || 0;
const str = x => String(x);
const isEmpty = xs => xs.length === 0;
const take = n => xs => xs.slice(0,n);
const drop = n => xs => xs.slice(n);
const reverse = xs => xs.slice(0).reverse();
const comp = f => g => x => f (g (x));
const not = x => !x;
const chunk = n => xs =>
  isEmpty(xs) ? [] : [take(n)(xs), ...chunk (n) (drop (n) (xs))];

"So these make it better?"

Look at how the code has cleaned up significantly

// NEW CODE (truncated)
return comp (chunk(3)) (reverse) (arr(n))
    .map(makeGroup)
    .map(thousand)
    .filter(comp(not)(isEmpty))
    .reverse()
    .join(' ');

// OLD CODE (truncated)
let grp = n => ('000' + n).substr(-3);
let rem = n => n.substr(0, n.length - 3);
let cons = xs => x => g => x ? [x, g && ' ' + g || '', ' ', xs].join('') : xs;
let iter = str => i => x => r => {
  if (x === '000' && r.length === 0) return str;
  return iter(cons(str)(fmt(x))(g[i]))
             (i+1)
             (grp(r))
             (rem(r));
};
return iter('')(0)(grp(String(n)))(rem(String(n)));

Most importantly, the utility functions we added in the new code can be used other places in your app. This means that, as a side effect of implementing numToWords in this way, we get the other functions for free. Bonus soda !

Some tests

console.log(numToWords(11009));
//=> eleven thousand nine

console.log(numToWords(10000001));
//=> ten million one 

console.log(numToWords(987));
//=> nine hundred eighty-seven

console.log(numToWords(1015));
//=> one thousand fifteen

console.log(numToWords(55111222333));
//=> fifty-five billion one hundred eleven million two hundred 
//   twenty-two thousand three hundred thirty-three

console.log(numToWords("999999999999999999999991"));
//=> nine hundred ninety-nine sextillion nine hundred ninety-nine
//   quintillion nine hundred ninety-nine quadrillion nine hundred
//   ninety-nine trillion nine hundred ninety-nine billion nine
//   hundred ninety-nine million nine hundred ninety-nine thousand
//   nine hundred ninety-one

console.log(numToWords(6000753512));
//=> six billion seven hundred fifty-three thousand five hundred
//   twelve

Runnable demo

const arr = x => Array.from(x);
const num = x => Number(x) || 0;
const str = x => String(x);
const isEmpty = xs => xs.length === 0;
const take = n => xs => xs.slice(0,n);
const drop = n => xs => xs.slice(n);
const reverse = xs => xs.slice(0).reverse();
const comp = f => g => x => f (g (x));
const not = x => !x;
const chunk = n => xs =>
  isEmpty(xs) ? [] : [take(n)(xs), ...chunk (n) (drop (n) (xs))];

// numToWords :: (Number a, String a) => a -> String
let numToWords = n => {
  
  let a = [
    '', 'one', 'two', 'three', 'four',
    'five', 'six', 'seven', 'eight', 'nine',
    'ten', 'eleven', 'twelve', 'thirteen', 'fourteen',
    'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen'
  ];
  
  let b = [
    '', '', 'twenty', 'thirty', 'forty',
    'fifty', 'sixty', 'seventy', 'eighty', 'ninety'
  ];
  
  let g = [
    '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion',
    'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion'
  ];
  
  // this part is really nasty still
  // it might edit this again later to show how Monoids could fix this up
  let makeGroup = ([ones,tens,huns]) => {
    return [
      num(huns) === 0 ? '' : a[huns] + ' hundred ',
      num(ones) === 0 ? b[tens] : b[tens] && b[tens] + '-' || '',
      a[tens+ones] || a[ones]
    ].join('');
  };
  
  let thousand = (group,i) => group === '' ? group : `${group} ${g[i]}`;
  
  if (typeof n === 'number')
    return numToWords(String(n));
  else if (n === '0')
    return 'zero';
  else
    return comp (chunk(3)) (reverse) (arr(n))
      .map(makeGroup)
      .map(thousand)
      .filter(comp(not)(isEmpty))
      .reverse()
      .join(' ');
};


console.log(numToWords(11009));
//=> eleven thousand nine

console.log(numToWords(10000001));
//=> ten million one 

console.log(numToWords(987));
//=> nine hundred eighty-seven

console.log(numToWords(1015));
//=> one thousand fifteen

console.log(numToWords(55111222333));
//=> fifty-five billion one hundred eleven million two hundred 
//   twenty-two thousand three hundred thirty-three

console.log(numToWords("999999999999999999999991"));
//=> nine hundred ninety-nine sextillion nine hundred ninety-nine
//   quintillion nine hundred ninety-nine quadrillion nine hundred
//   ninety-nine trillion nine hundred ninety-nine billion nine
//   hundred ninety-nine million nine hundred ninety-nine thousand
//   nine hundred ninety-one

console.log(numToWords(6000753512));
//=> six billion seven hundred fifty-three thousand five hundred
//   twelve

You can transpile the code using babel.js if you want to see the ES5 variant

Solution 3:

I spent a while developing a better solution to this. It can handle very big numbers but once they get over 16 digits you have pass the number in as a string. Something about the limit of JavaScript numbers.

    function numberToEnglish( n ) {
        
        var string = n.toString(), units, tens, scales, start, end, chunks, chunksLen, chunk, ints, i, word, words, and = 'and';

        /* Remove spaces and commas */
        string = string.replace(/[, ]/g,"");

        /* Is number zero? */
        if( parseInt( string ) === 0 ) {
            return 'zero';
        }
        
        /* Array of units as words */
        units = [ '', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'eleven', 'twelve', 'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen' ];
        
        /* Array of tens as words */
        tens = [ '', '', 'twenty', 'thirty', 'forty', 'fifty', 'sixty', 'seventy', 'eighty', 'ninety' ];
        
        /* Array of scales as words */
        scales = [ '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion', 'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion', 'decillion', 'undecillion', 'duodecillion', 'tredecillion', 'quatttuor-decillion', 'quindecillion', 'sexdecillion', 'septen-decillion', 'octodecillion', 'novemdecillion', 'vigintillion', 'centillion' ];
        
        /* Split user argument into 3 digit chunks from right to left */
        start = string.length;
        chunks = [];
        while( start > 0 ) {
            end = start;
            chunks.push( string.slice( ( start = Math.max( 0, start - 3 ) ), end ) );
        }
        
        /* Check if function has enough scale words to be able to stringify the user argument */
        chunksLen = chunks.length;
        if( chunksLen > scales.length ) {
            return '';
        }
        
        /* Stringify each integer in each chunk */
        words = [];
        for( i = 0; i < chunksLen; i++ ) {
            
            chunk = parseInt( chunks[i] );
            
            if( chunk ) {
                
                /* Split chunk into array of individual integers */
                ints = chunks[i].split( '' ).reverse().map( parseFloat );
            
                /* If tens integer is 1, i.e. 10, then add 10 to units integer */
                if( ints[1] === 1 ) {
                    ints[0] += 10;
                }
                
                /* Add scale word if chunk is not zero and array item exists */
                if( ( word = scales[i] ) ) {
                    words.push( word );
                }
                
                /* Add unit word if array item exists */
                if( ( word = units[ ints[0] ] ) ) {
                    words.push( word );
                }
                
                /* Add tens word if array item exists */
                if( ( word = tens[ ints[1] ] ) ) {
                    words.push( word );
                }
                
                /* Add 'and' string after units or tens integer if: */
                if( ints[0] || ints[1] ) {
                    
                    /* Chunk has a hundreds integer or chunk is the first of multiple chunks */
                    if( ints[2] || ! i && chunksLen ) {
                        words.push( and );
                    }
                
                }
                
                /* Add hundreds word if array item exists */
                if( ( word = units[ ints[2] ] ) ) {
                    words.push( word + ' hundred' );
                }
                
            }
            
        }
        
        return words.reverse().join( ' ' );
        
    }


// - - - - - Tests - - - - - -
function test(v) {
  var sep = ('string'==typeof v)?'"':'';
  console.log("numberToEnglish("+sep + v.toString() + sep+") = "+numberToEnglish(v));
}
test(2);
test(721);
test(13463);
test(1000001);
test("21,683,200,000,621,384");

Related

What are the differences between JSON and JavaScript object? [duplicate]
Concatenate columns in Apache Spark DataFrame
MVC3 and Entity Framework
remove objects from array by object property
Using Regular Expressions to Extract a Value in Java
Size-limited queue that holds last N elements in Java
base64 encoded images in email signatures
What's the difference of name scope and a variable scope in tensorflow?
How can I create a copy of an Oracle table without copying the data?
System.MissingMethodException: Method not found?
Request format is unrecognized for URL unexpectedly ending in
Does height and width not apply to span?