We Keep Coding

Removing zeros after comma based on maximum consequent zeros

I have a page with a grid where user's numbers get saved. It has a following pattern - every number ends with 3 digits after comma. It doesn't look nice, when for example user's input is
123,450
123,670
123,890
It's much better to have just 2 numbers after comma, because last 0 is absolutely meaningless and redundant.
The way it still should have 3 digits is only if at least one element in an array doesn't end up with 0
For example:
123,455
123,450
123,560
In this case 1st element of the array has the last digit not equal to 0 and hence all the elements should have 3 digits. The same story with 2 or 1 zeros
Zeros are redundant:
123,30
123,40
123,50
Zeros are necessary:
123,35
123,40
123,50
The question is how can I implement it programatically? I've started like this:
var zeros2Remove = 0;
numInArray.forEach(function(item, index, numInArray)
{
var threeDigitsAfterComma = item.substring(item.indexOf(',') + 1);
for(var j = 2; j <= 0; j--)
{
if(threeDigitsAfterComma[j] == 0)
{
zeros2Remove =+ 1;
}
else //have no idea what to do..
}
})
Well in my implementation I don't know how to do it since I have to iterate through every element but break it if at least 1 number has a last digit equal to zero.. In order to do that I have to break outer loop, but don't know how and I'm absolutely sure that I don't have to...

I think the following code what you are looking for exactly , please manipulate numbers and see the changes :
var arr = ["111.3030", "2232.0022", "3.001000", "4","558.0200","55.00003000000"];
var map = arr.map(function(a) {
if (a % 1 === 0) {
var res = "1";
} else {
var lastNumman = a.toString().split('').pop();
if (lastNumman == 0) {
var m = parseFloat(a);
var res = (m + "").split(".")[1].length;
} else {
var m = a.split(".")[1].length;
var res = m;
}
}
return res;
})
var maxNum = map.reduce(function(a, b) {
return Math.max(a, b);
});
arr.forEach(function(el) {
console.log(Number.parseFloat(el).toFixed(maxNum));
});

According to MDN,
There is no way to stop or break a forEach() loop other than by throwing an exception. If you need such behavior, the forEach() method is the wrong tool. Use a plain loop or for...of instead.
If you convert your forEach loop to a for loop, you can break out of it with a label and break statement:
// unrelated example
let i;
let j;
outerLoop:
for (i = 2; i < 100; ++i) {
innerLoop:
for (j = 2; j < 100; ++j) {
// brute-force prime factorization
if (i * j === 2183) { break outerLoop; }
}
}
console.log(i, j);
I gave you an unrelated example because your problem doesn't need nested loops at all. You can find the number of trailing zeroes in a string with a regular expression:
function getTrailingZeroes (str) {
return str.match(/0{0,2}$/)[0].length;
}
str.match(/0{0,2}$/) finds between 0 and 2 zeroes at the end of str and returns them as a string in a one-element array. The length of that string is the number of characters you can remove from str. You can make one pass over your array of number-strings, breaking out when necessary, and use Array.map as a separate truncation loop:
function getShortenedNumbers (numInArray) {
let zeroesToRemove = Infinity;
for (const str of numInArray) {
let candidate = getTrailingZeroes(str);
zeroesToRemove = Math.min(zeroesToRemove, candidate);
if (zeroesToRemove === 0) break;
}
return numInArray.map(str => str.substring(0, str.length - zeroesToRemove);
}
All together:
function getTrailingZeroes (str) {
return str.match(/0{0,2}$/)[0].length;
}
function getShortenedNumbers (numInArray) {
let zeroesToRemove = Infinity;
for (const str of numInArray) {
let candidate = getTrailingZeroes(str);
zeroesToRemove = Math.min(zeroesToRemove, candidate);
if (zeroesToRemove === 0) break;
}
return numInArray.map(str => str.substring(0, str.length - zeroesToRemove));
}
console.log(getShortenedNumbers(['123,450', '123,670', '123,890']));
console.log(getShortenedNumbers(['123,455', '123,450', '123,560']));

This solution might seem a little cumbersome but it should work for all possible scenarios. It should be easy enough to make always return a minimal number of decimals places/leading zeros.
I hope it helps.
// Define any array
const firstArray = [
'123,4350',
'123,64470',
'123,8112390',
]
const oneOfOfYourArrays = [
'123,30',
'123,40',
'123,50',
]
// Converts 123,45 to 123.45
function stringNumberToFloat(stringNumber) {
return parseFloat(stringNumber.replace(',', '.'))
}
// For 123.45 you get 2
function getNumberOfDecimals(number) {
return number.split('.')[1].length;
}
// This is a hacky way how to remove traling zeros
function removeTralingZeros(stringNumber) {
return stringNumberToFloat(stringNumber).toString()
}
// Sorts numbers in array by number of their decimals
function byNumberOfValidDecimals(a, b) {
const decimalsA = getNumberOfDecimals(a)
const decimalsB = getNumberOfDecimals(b)
return decimalsB - decimalsA
}
// THIS IS THE FINAL SOLUTION
function normalizeDecimalPlaces(targetArray) {
const processedArray = targetArray
.map(removeTralingZeros) // We want to remove trailing zeros
.sort(byNumberOfValidDecimals) // Sort from highest to lowest by number of valid decimals
const maxNumberOfDecimals = processedArray[0].split('.')[1].length
return targetArray.map((stringNumber) => stringNumberToFloat(stringNumber).toFixed(maxNumberOfDecimals))
}
console.log('normalizedFirstArray', normalizeDecimalPlaces(firstArray))
console.log('normalizedOneOfOfYourArrays', normalizeDecimalPlaces(oneOfOfYourArrays))

Try this
function removeZeros(group) {
var maxLength = 0;
var newGroup = [];
for(var x in group) {
var str = group[x].toString().split('.')[1];
if(str.length > maxLength) maxLength = str.length;
}
for(var y in group) {
var str = group[y].toString();
var substr = str.split('.')[1];
if(substr.length < maxLength) {
for(var i = 0; i < (maxLength - substr.length); i++)
str += '0';
}
newGroup.push(str);
}
return newGroup;
}
Try it on jsfiddle: https://jsfiddle.net/32sdvzn1/1/
My script checks the length of every number decimal part, remember that JavaScript removes the last zeros in a decimal number, so 3.10 would be 3.1, so the length is less when there is a number with zeros in the end, in this case we just add a zero to the number.
Update
I've updated the script, the new version adds as much zeros as the different between the max decimal length and the decimal length of the analyzed number.
Example
We have: 3.11, 3.1423, 3.1
The max length would be: 4 (1423)
maxLenght (4) - length of .11 (2) = 2
We add 2 zeros to 3.11, that will become 3.1100

I think you can start out assuming you will remove two extra zeros, and loop through your array looking for digits in the last two places. With the commas, I'm assuming your numArray elements are strings, all starting with the same length.
var numArray = ['123,000', '456,100', '789,110'];
var removeTwo = true, removeOne = true;
for (var i = 0; i < numArray.length; i++) {
if (numArray[i][6] !== '0') { removeTwo = false; removeOne = false; }
if (numArray[i][5] !== '0') { removeTwo = false; }
}
// now loop to do the actual removal
for (var i = 0; i < numArray.length; i++) {
if (removeTwo) {
numArray[i] = numArray[i].substr(0, 5);
} else if (removeOne) {
numArray[i] = numArray[i].substr(0, 6);
}
}

Random Selection from Array into new Array

I have seen this question answered here, but I have an additional question that is related.
Im trying to achieve:
the same thing, but, with the output being a selection of more than 1 number, the above works fine if you only want a single value returned.
How can I return (x) amount of outputs #7 in this case into a new var or array ...? Some guidance on best practice will also be appreciated ;)
Thanks a bunch....
Just for fun,
Objective:
Create a teeny weenie web App that returns 7 variable numbers in a range [ 1 - 49 ] into an array.
`
Think return a list of Lotto Numbers
Create new array from selection using _underscore.js [Sample function]
**** I know this is easier, but im trying to get an understanding
of using Vanilla JS to accomplish this
_.sample([1, 2, 3, 4, 5, 6], 3); => [1, 6, 2]
var getLoot = Array.from(Array(50).keys()) // Create array of 49 numbers.
console.info(getLoot);
var pick = getLoot[Math.floor(Math.random() * getLoot.length)];
pick;
// pick returns a single which is fine if you want a single but, ..
// I want something like this :
var pick = function() {
// code that will return 7 numbers from the array into a new Array
// will randomize every time pick is called...
}

If you want to return more than just 1 value you can store your results into a data structure like an array. Here is a solution to the problem
assuming you can pass in your array of 50 numbers into the pick() funciton.:
var getRandomArbitrary = function(min, max) {
return Math.floor(Math.random() * (max - min) + min);
}
var pick = function(fiftyNumberArray, numberOfValuesWanted) {
var randomNums = [];
for(var i = 0; i < numberOfValuesWanted; i++) {
randomNums.push(
fiftyNumberArray[getRandomArbitrary(0, 50)]
);
}
return randomNums;
};
var fiftyNumbers = [] // <- set your array of fifty numbers
pick(fiftyNumbers, 7);
Javascript's Math.random() will return a value in between 0 and 1 (exclusive). So to get an index scaled up to the correct value to look into your array, you would want to multiply that by the formula (max - min) + min

You can use Array.prototype.splice(), Math.floor(), Math.random(), for loop to remove elements from input array, return an array containing pseudo randomly picked index from input array without duplicate indexes being selected.
function rand(n) {
var res = []; var a = Array.from(Array(n).keys());
for (;a.length;res.push(a.splice(Math.floor(Math.random()*a.length),1)[0]));
return res
}
console.log(rand(50));

One good way of doing this job is shuffling the array and picking the first n values. Such as;
function shuffle(a){
var i = a.length,
j,
tmp;
while (i > 1) {
j = Math.floor(Math.random()*i--);
tmp = a[i];
a[i] = a[j];
a[j] = tmp;
}
return a;
};
var arr = Array(50).fill().map((_,i) => i+1); //[1,2,3...49,50]
randoms = shuffle(arr).slice(0,7) // to get 7 random numbers from arrary arr
console.log(randoms)

This is probably what you want.
$(function()
{
var lol = [1,4,5,6,7,8,9];
function getPart(array,number)
{
var part = [],
index;
while(true)
{
if(part.length == number)
{
break;
}
index = $.random(0,part.length);
part.push(lol.splice(index,1));
}
return part;
}
});
$.random = function(min,max,filter)
{
var i,
n = Math.floor(Math.random()*(max-min+1)+min);
if(filter != undefined && filter.constructor == Array)
{
for(i=filter.length-1;i>-1;i--)
{
if(n == filter[i])
{
n = Math.floor(Math.random()*(max-min+1)+min)
i = filter.length;
}
}
}
return n;
}

Accessing indexes of a string inside an array and taking the sum

Ok so I am trying to access each individual number in the strings inside of this array.
var array = ['818-625-9945','999-992-1313','888-222-2222','999-123-1245'];
var str = "";
for (i=0; i<array.length; i++) {
str = array[i];
}
The problem is that this is the output: '999-992-1313'
and not the first element array[0]: '818-625-9945'
When I try doing a nested for loop to go through each element inside the string I am having trouble stating those elements.
var array = ['818-625-9945','999-992-1313','888-222-2222','999-123-1245'];
for (i=0; i<array.length; i++) {
for (j=0; j<array[i].length; j++) {
console.log(array[i][j]);
}
}
I do not know how to access each individual number inside of the string array[i]. I would like to find a way to make a counter such that if I encounter the number '8' I add 8 to the total score, so I can take the sum of each individual string element and see which number has the highest sum.
var array = ['818-625-9945','999-992-1313','888-222-2222','999-123-1245'];
for (i=0; i<array.length; i++) {
for (j=0; j<array[i].length; j++) {
if (array[i](j).indexOf('8') !== -1) {
// add one to total score
// then find a way to increase the index to the next index (might need help here also please)
}
}
}

Mabe this works for you. It utilized Array.prototype.reduce(), Array.prototype.map() and String.prototype.split().
This proposal literates through the given array and splits every string and then filter the gotten array with a check for '8'. The returned array is taken as count and added to the return value from the former iteration of reduce - and returned.
var array = ['818-625-9945', '999-992-1313', '888-222-2222', '999-123-1245'],
score = array.reduce(function (r, a) {
return r + a.split('').filter(function (b) { return b === '8'; }).length;
}, 0);
document.write('Score: ' + score);
A suggested approach with counting all '8' on every string:
var array = ['818-625-9945', '999-992-1313', '888-222-2222', '999-123-1245'],
score = array.map(function (a) {
return a.split('').filter(function (b) { return b === '8'; }).length;
});
document.write('Score: ' + score);

Actually rereading your question gave me a better idea of what you want. You simply want to count and retrieve the number of 8's per string and which index in your array conforms with this maximum 8 value. This function retrieves the index where the value was found in the array, how many times 8 was found and what is the string value for this result. (or returns an empty object in case you give in an empty array)
This you could easily do with:
'use strict';
var array = ['818-625-9945', '999-992-1313', '888-222-2222', '999-123-1245'];
function getHighestEightCountFromArray(arr) {
var max = 0,
result = {};
if (arr && arr.forEach) {
arr.forEach(function(value, idx) {
var cnt = value.split('8').length;
if (max < cnt) {
// found more nr 8 in this section (nl: cnt - 1)
max = cnt;
// store the value that gave this max
result = {
count: cnt - 1,
value: value,
index: idx
};
}
});
}
return result;
}
console.log(getHighestEightCountFromArray(array));
The only thing here is that when an equal amount of counts is found, it will still use the first one found, here you could decide which "maximum"
should be preferred(first one in the array, or the newest / latest one in the array)
OLD
I'm not sure which sums you are missing, but you could do it in the following way.
There I first loop over all the items in the array, then I use the String.prototype.split function to split the single array items into an array which would then contain ['818', '625', '9945']. Then for each value you can repeat the same style, nl: Split the value you are receiving and then loop over all single values. Those then get convert to a number by using Number.parseInt an then all the values are counted together.
There are definitelly shorter ways, but this is a way how you could do it
'use strict';
var array = ['818-625-9945','999-992-1313','888-222-2222','999-123-1245'],
sumPerIndex = [],
totalSum = 0;
array.forEach(function(item, idx) {
var values = item.split('-'), subArray = [], itemSum = 0;
values.forEach(function(value) {
var singleItems = value.split(''),
charSum = 0;
singleItems.forEach(function(char) {
charSum += parseInt(char);
});
itemSum += charSum;
subArray.push(charSum);
console.log('Sum for chars of ' + value + ' = ' + charSum);
});
sumPerIndex.push(subArray);
totalSum += itemSum;
console.log('Sum for single values of ' + item + ' = ' + itemSum);
});
console.log('Total sum of all elements: ' + totalSum);
console.log('All invidual sums', sumPerIndex);

Pick m integers randomly from an array of size n in JS

Problem (from Cracking the Coding Interview): Write a method to randomly generate a set of m integers from an array of size n.
Each element must have equal probability of being chosen.
I'm implementing my answer in JS. For the recursive function, the code sometimes returns undefined as one of the elements in the array.
My JS Code
var pickMRecursively = function(A, m, i) {
if (i === undefined) return pickMRecursively(A, m, A.length);
if (i+1 === m) return A.slice(0, m);
if (i + m > m) {
var subset = pickMRecursively(A, m, i-1);
var k = rand(0, i);
if (k < m) subset[k] = A[i];
return subset;
}
return null;
};
Given Java Solution
int[] pickMRecursively(int[] original, int m,int i) {
if (i +1==m){// Basecase
/* return first m elements of original */
} elseif(i+m>m){
int[] subset = pickMRecursively(original, m, i - 1);
int k = random value between 0 and i, inclusive
if(k<m){
subset[k] = original[i]j
}
return subset;
}
return null;
}

I hate these questions because sometime they're often deliberately vague - I'd ask "What type of data is in the array?". But if this is actually a question about randomly re-ordering an array, then in JavaScript, given that arr is an array of numbers, of which some/all might not be integers...
function generateM(arr) {
var hold = [];
var m = [];
var n = arr.length;
var grab;
// clone arr >> hold
while(n--) {
hold[n] = arr[n];
}
n = hold.length;
// select randomly from hold
while(n--) {
grab = hold.splice(Math.floor(Math.random()*n),1)[0];
// ensure integers
m.push(Math.round(grab));
}
return m;
}
The array arr is cloned here to cover scoping issues and to produce a fresh collection, not reorder an existing one.
ADDIT: Alternatively, if this is just asking for a set of m.length random integers generated from an array of n.length, then it doesn't matter what the content of the array actually is and the range of possible (randomly generated) values will be (could be?) 0 - n.length, so...
function generateM(arr, M) {
var aLen = arr.length;
var m = [];
do {
m.push(Math.round(Math.random() * aLen));
} while(M--);
return m;
}
...but that seems like a stupid, pointless challenge. The data in the 'array of size n' is quite important here it seems to me.

how can i make my function more efficient?

hey guys i wrote a function that compares array values and returns the minimum value but i want to know if there are ways to make it more efficient like iterating through all arrays (using one loop) and putting the results in a new array or making individual arrays sub-arrays of a single array, etc. Also the function provides the correct output but prints the answer three times:
var nums1 = [-7528819, 3927361, -6398192];
var nums2 = [1777100, -2299720, -5566643];
var nums3 = [7188445, 3724971, 7699332];
var nums4 = [-8432528, -159836, -1604959];
var nums5 = [2764889, 4681472, 701396];
var nums6 = [-5073513, 599535, 4388457];
var nums7 = [8689640, 8028586, 1022322];
var nums8 = [-1088592, 1211232, -7868192];
var nums9 = [-5848613, -4945165, 631213];
var nums10 = [3218429, -833619, -1495854];
var nums11 = [8007060, 1637562, -7568493];
var nums12 = [-8391131, -6585338, 131787];
var nums13 = [-3957775, -9396892, -6143241];
var nums14 = [-6258442, -7829421, 3696922];
var nums15 = [2136598, 4935467, -1621605];
var nums16 = [-7162005, 9861954, 8977930];
var nums17 = [7226452, 8551594, 7006517];
var nums18 = [-1751226, -2536997, -1782251];
var nums19 = [380582, 1614389, 3272584];
var nums20 = [-8988205, -5167181, -7561034];
var nums21 = [-484059, -7160121, 4076528];
var nums22 = [1947448, -5551253, 7491190];
var numsLength = nums1.length;
var i = 0;
var minNum;
function test(arr) {
for (i; i < numsLength; i++) {
if (arr[0] < arr[1] && arr[2]) {
minNum = arr[0];
} else if (arr[1] < arr[2] && arr[0]) {
minNum = arr[1];
} else if (arr[2] < arr[1] && arr[0]) {
minNum = arr[2];
}
console.log(minNum);
}
}
test(nums1);

You could just use Math.min function.
console.log(Math.min.apply(null, nums1));

Look at his snippet of code and read inline comments:
var nums = [];
// I'm pushing only 3 sets of data, but there can be any number
// Also there can be any number of elements in each array as you can see
nums.push([-7528819, 3927361, -6398192]);
nums.push([1777100, -2299720, -5566643, 380582]);
nums.push([7188445, 3724971, 7699332, 1947448, -5551253, 7491190]);
function produceResults(nums) {
var i,
results = [];
// gathering results
for (i = 0; i < nums.length; i++) {
results.push(Math.min.apply(null, nums[i]));
}
return results;
}
console.log(produceResults(nums));
So 2 suggestions:
use more dynamic structure (array of arrays) instead of
defining 22 arrays.
use built in JS functions and components (Math.min)

Unrolling a loop is actually the most efficient implementation of a loop in most cases. However, practically speaking, unrolling a loop isn't usually feasible. With a small, fixed-size array, like those you have here, each permutation of the loop is obvious, and if your goal is raw speed you can't get much more efficient than what you have. That being said, the loop in your function is useless, as others have pointed out., because you've essentially unrolled the loop already. Also the syntax of the if statement is incorrect, and you are not handling the case where values in the array are equal. For fixed arrays of size three you want something more along the lines of...
if (val1 <= val2 && val1 <= val3) {
minVal = val1;
} else if (val2 <= val1 && val2 <= val3) {
minVal = val2;
} else minVal = val3;
Now if you want to do an arbitrary search for the min value of any size array you would do something similar, but using a loop, like...
var minVal = null;
for (var i = 0; i < arr.length; i++) {
if (minVal === null || minVal > (val = arr[i]))
minVal = val;
}
Depending on what you actually want to accomplish, and the size of the array, it might make sense to sort the array and rerurn the min (0 index) from the sorted array. If you go that route, start with a google search for "sort algorithms"