Develop Reference

Javascript - Permutations remove the duplicates elements

that is found here in stack but i want somes changes.
function perms(data) {
if (!(data instanceof Array)) {
throw new TypeError("input data must be an Array");
}
data = data.slice(); // make a copy
var permutations = [],
stack = [];
function doPerm() {
if (data.length == 0) {
permutations.push(stack.slice());
}
for (var i = 0; i < data.length; i++) {
var x = data.splice(i,1);
stack.push(x);
doPerm();
stack.pop();
data.splice(i, 0, x);
}
}
doPerm();
return permutations;
}
var input = "552".split('');
var result = perms(input);
for (var i = 0; i < result.length; i++) {
result[i] = result[i].join('-');
}
The result of that is :
5-5-2
5-2-5
5-5-2
5-2-5
2-5-5
2-5-5
but , are 3 elements duplicates the result must be :
5-5-2
5-2-5
2-5-5
how can i fix that issue .

Basically, you have one issue,
var x = data.splice(i, 1)[0];
// ^^^ is missing
because you get an array with splicing. The result is a deep nested array with
data.splice(i, 0, x);
This inserts the array later on position i.
For preventing duplicates, you need a check, if the actual value is already inserted in the result set with
permutations.some(function (a) {
return a.every(function (b, j) {
return stack[j] === b;
});
}) || permutations.push(stack.slice());
which test the arrays and if no match, the push is performed.
function perms(data) {
if (!(data instanceof Array)) {
throw new TypeError("input data must be an Array");
}
data = data.slice(); // make a copy
var permutations = [],
stack = [],
hash = Object.create(null);
function doPerm() {
if (data.length == 0) {
permutations.some(function (a) {
return a.every(function (b, j) {
return stack[j] === b;
});
}) || permutations.push(stack.slice());
return;
}
for (var i = 0; i < data.length; i++) {
var x = data.splice(i, 1)[0];
stack.push(x);
doPerm();
stack.pop();
data.splice(i, 0, x);
}
}
doPerm();
return permutations;
}
var input = "552".split('');
var result = perms(input);
for (var i = 0; i < result.length; i++) {
result[i] = result[i].join('-');
}
console.log(result);

Check if array array is present within resulting array before calling .push() using Array.prototype.some(), Array.prototype.join()
function p(a, b, res) {
var b = b || [],
res = res || [],
len = a.length;
if (!len) {
// check if `res` contains `b.join("")`
if (!res.length
|| !res.some(function(n) {
return n.join("") === b.join("")
}))
res.push(b)
} else {
for (var i = 0
; i < len; p(a.slice(0, i).concat(a.slice(i + 1, len))
, b.concat(a[i]), res)
, i++);
}
return res
}
var result = p("552".split(""));
result = result.map(function(res) {
return res.join("-")
});
console.log(result);

javascript array - increment value at given key

I have a dynamic array and I am trying to increment the value by 1 if the key exists in the array. According to my debug it is incrementing the key and and creating a second key/value pair.
A snippet of my code:
for (var i = 0; i < choices.length; i++) {
console.log(choices[i]);
if (choices[i].YearTermId == 1) {
if (!lookup(firstChoice, choices[i].FirstChoiceOptionId)) {
firstChoice.push({
key: choices[i].FirstChoiceOptionId,
value: 1
});
} else {
firstChoice[choices[i].FirstChoiceOptionId] = firstChoice[choices[i].FirstChoiceOptionId] + 1;
}
more if/else..
function lookup( arr, name ) {
for(var i = 0, len = arr.length; i < len; i++) {
if( arr[ i ].key === name )
return true;
}
return false;
}

You're using an array where you should be using an object. If you use an object, your code can be rewritten as:
var firstChoice = {};
for (var i = 0; i < choices.length; i++) {
var firstChoiceOptionId = choices[i].FirstChoiceOptionId;
if (choices[i].YearTermId == 1) {
firstChoice[firstChoiceOptionId] = firstChoice[firstChoiceOptionId]
? firstChoice[firstChoiceOptionId] + 1
: 1;
/* ... */
}
}
If you need the data as an array afterwards, just map it:
var firstChoiceArray = Object.keys(firstChoice).map(function(key) {
return {
key: key,
value: firstChoice[key]
};
});
Conversely, if you have an input array and want to convert it to an object for manipulation, reduce it:
var firstChoice = firstChoiceArray.reduce(function(result, current) {
result[current.key] = current.value;
return result;
}, {});

I think you should increment value key, like:
firstChoice[choices[i].FirstChoiceOptionId].value ++;
And I would like to rewrite this code to:
var firstChoice = {};
for (var i = 0; i < choices.length; i++) {
if (choices[i].YearTermId == 1) {
if (!firstChoice[choices[i].FirstChoiceOptionId]) {
firstChoice[choices[i].FirstChoiceOptionId] = 0;
}
firstChoice[choices[i].FirstChoiceOptionId]++;
}
}
console.log(firstChoice);

Try with Array.map:
Example:
var a = [{key:"ab","value":1},{key:"cd","value":1},{key:"ef","value":1}];
a.map(function(item){if(item.key == this){item.value++}}, "cd");
So, a[1] will have value 2 after that.

How can I return the longest string in an array—even if the array contains items that are not strings?

Let's say I'm writing a function like so:
function longestString (someArray) {
// code
}
If someArray = ['word','longer phrase',['a','b','c'],1234567891011121314151617], I would want the function to only return the longest string in the array and ignore the integers and other arrays that may also lie within it. I tried this:
function longestString (someArray) {
return someArray.sort(function (a, b) { return b.length - a.length; })[0];
}
It didn't work, and I am now stuck. :/

Filter only string element and do it
function longestString (someArray) {
return someArray
.filter(function(a){ return typeof(a)=='string' })
.sort(function (a, b) { return b.length - a.length; })[0];
}

Try this:
function longestString(someArray) {
var result = "";
for (var i = 0; i < someArray.length; i++) {
if ((typeof someArray[i] === "string") && (someArray[i].length > result.length)) {
result = someArray[i];
}
}
return result;
}

try to do :
function longestString (someArray) {
$longest_string = '';
foreach ($someArray as $value)
{
$current_length = strlen($longest_string);
if(strlen($value) > $current_length ) $longest_string = $value;
}
return $longest_string;
}

Try this.
var a = ['word', 'longer phrase', ['a', 'b', 'c'], 1234567891011121314151617];
returnLongestString(a);
function returnLongestString(arr) {
var longestString = '';
for (var i = 0; i < arr.length; i++) {
if (typeof arr[i] == "string" && arr[i].length > longestString.length) {
longestString = arr[i];
}
};
return longestString;
}

When I saw this question, it had 0 answers, when I finished writing and testing my function, there were five. But this is my approach:
The key here is to first filter only the strings. Then, list all the lengths on an array. Then using that array you can get a match on the bigger one.
function longestString (someArray) {
//we only need strings, so first we will filter all the data
var stringsOnly = [];
for (var i = 0; i < someArray.length; i++) {
if(typeof(someArray[i]) === 'string'){
stringsOnly.push(someArray[i]);
}
};
//Now with an array of just strings, we can get their indivial lenghts
var stringLengths = [];
for (var i = 0; i < stringsOnly.length; i++) {
var currentString = stringsOnly[i];
stringLengths.push(currentString.length);
};
//Get the max length
var maxLength = Math.max.apply(Math,stringLengths);
//get a string wich length equals to maxLength
for (var i = 0; i < stringsOnly.length; i++) {
var theString = stringsOnly[i];
if(theString.length === maxLength){return theString};
};
}
This function will return the largest string. If more than one string have the same length, It will return the first one. However, if you want to get various strings, you could make some little modificationson the function above:
function multipleLongestString (someArray) {
//we only need strings, so first we will filter all the data
var stringsOnly = [];
for (var i = 0; i < someArray.length; i++) {
if(typeof(someArray[i]) === 'string'){
stringsOnly.push(someArray[i]);
}
};
//Now with an array of just strings, we can get their indivial lenghts
var stringLengths = [];
for (var i = 0; i < stringsOnly.length; i++) {
var currentString = stringsOnly[i];
stringLengths.push(currentString.length);
};
//Get the max length
var maxLength = Math.max.apply(Math,stringLengths);
//modification here
longests = [];
//get a string wich length equals to maxLength
for (var i = 0; i < stringsOnly.length; i++) {
var theString = stringsOnly[i];
if(theString.length === maxLength){longests.push(theString)};
};
return longests;
}
That is an extra that may help you later. But if you just want the largest one, use the first function. I hope that my answer is relevant.
:)

Heres my approach at it. Really all you want to know is if the phrase is longer than the previous and if its a string.
jsFiddle here.
var someArray = ['word','longer phrase',['a','b','c'],1234567891011121314151617]
var longestString = function(arr) {
var longest = "";
for (var i = 0; i < arr.length; i++) {
var value = arr[i];
if (typeof value === "string") {
longest = arr[i];
}
}
alert(longest);
}
longestString(someArray);

Pass by reference?

Can anyone tell me why all the object.num's print as 1? This is driving me mad. Somehow after the for loop the values of the object.num = 1 no matter what, even though they are never set to 1. Please copy the entire segment to debug.
<script type="text/javascript">
window.addEventListener("load", main, false);
const n = 4;
function main()
{
var belt = new Array(4*n);
initArr(belt);
printIt(belt);
populateArr(belt);
printIt(belt);
reorder(belt);
printIt(belt);
}
function populateArr(arr)
{
var a = {name:"a", num:0};
var b = {name:"b", num:0};
var end = arr.length;
var i = end-1;
for(var temp = n; temp > 0; temp--)
{
a.num = temp;
arr[i] = a;
i-=2;
}
i = end-2;
for(var temp = n; temp > 0; temp--)
{
b.num = temp;
arr[i] = b;
i-=2;
}
return arr;
}
function printIt(arr)
{
var tempArr = new Array(arr.length);
for(var i=0; i < arr.length; i++)
{
tempArr[i] = arr[i].name + arr[i].num;
}
console.log(tempArr);
}
function initArr(arr)
{
var nothing = {name:null, num:0};
for(var i=0; i<arr.length; i++)
{
arr[i] = nothing;
}
return arr;
}
function reorder(arr)
{
var nothing = {name:null, num:0};
var counter = 0;
var aIndex = 0;
var bIndex = null;
for(var i=0; i < arr.length; i++)
{
if(arr[i].name === "b" && bIndex === null)//first b doesn't get moved
{
bIndex = i+1;
}
else if(arr[i].name === "a")
{
arr[aIndex] = arr[i];
arr[i] = nothing;
counter++;
aIndex++;
}
else if(arr[i].name ==="b")
{
arr[bIndex] = arr[i];
arr[i] = nothing;
counter++;
bIndex++;
}
}
console.log("count: " + counter);
console.log("n: " + n);
return arr;
}
</script>

Somehow after the for loop the values of the object.num = 1 no matter what, even though they are never set to 1.
Yes "they" are - "they're" set to 1 in the last iteration of this loop:
for(var temp = n; temp > 0; temp--)
{
a.num = temp;
arr[i] = a;
i-=2;
}
The last iteration of that loop is when temp is 1.
Now, you've only actually got one object - and you're setting every element of the array to be a reference to that object. That's why all the values in the array look the same. If you want to create a different object each time, you should use:
for(var temp = n; temp > 0; temp--)
{
arr[i] = { name: "a", num: temp };
i -= 2;
}

Why is this happening with javascript objects

I am working on a function to map a string that has been split into an array
function arrayDups(a) // a: array to search: as in string split into array.
{
var unique = {}
var dups = [];
var seen = false;
var bypass = {};
for(var i = 0; i < a.length; i++)
{
if(bypass[a[i]] == 'undefined')
{
unique[a[i]] = i+',';
bypass[a[i]] = false;
}
for(var k = i; k < a.length; k++)
{
// so the same char later will not produce duplicate records.
if(unique[a[k]] != 'undefined' && bypass[a[k]] != 'undefined' && !bypass[a[k]])
{
unique[a[k]] += k+',';
if(k == a.length - 1)
{
bypass[a[i]] = true
}
}
}
}
for(var x in unique)
{
dups[dups.length] = x+':'+unique[x]
}
return dups;
}
this is colled in the following context
var testCase = ('disproportionate').split('');
window.onload = function()
{
var test = document.getElementById('res')
test.childNodes[0].data = arrayDups(testCase).join("\n")
}
which produces the following output
d:undefined0,
i:undefined1,10,1,10,
s:undefined2,2,2,
p:undefined3,6,3,6,3,6,3,6,
r:undefined4,8,4,8,4,8,4,8,4,8,
o:undefined5,7,11,5,7,11,5,7,11,5,7,11,5,7,11,5,7,11,
t:undefined9,14,9,14,9,14,9,14,9,14,9,14,9,14,9,14,9,14,9,14,
n:undefined12,12,12,12,12,12,12,12,12,12,12,12,12,
a:undefined13,13,13,13,13,13,13,13,13,13,13,13,13,13,
e:undefined15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
The questions:
where is undefined coming from
and why are the index positions being duplicated when for each iteration of i
k begins at the current i value and should be looking ahead to find index values of duplicate chars
I wouldn't want to answer my own question so I am adding to the original post via edits
Here is what I came up with
function arrayDups(a) // a: array to search: as in string split into array.
{
var unique = {}
var dups = [];
var seen = false;
var bypass = {};
for(var i = 0; i < a.length; i++)
{
if(!bypass.propertyIsEnumerable(a[i]))
{
unique[a[i]] = i+',';
bypass[a[i]] = 'false';
continue;
}
if(bypass.propertyIsEnumerable(a[i]) && bypass[a[i]] == 'false')
{
for(var k = i; k < a.length; k++)
{
// for every instance of a[i] == a[k] unique[a[k]] will be defined
if(a[i] == a[k] && unique.propertyIsEnumerable(a[k]))
{
unique[a[k]] += k+',';
}
if(k == a.length - 1)
{
bypass[a[i]] = 'true'
continue;
}
}
}
}
for(var x in unique)
{
dups[dups.length] = x+':'+unique[x]
}
return dups;
}
And this is the output
d:0,
i:1,10,
s:2,
p:3,6,
r:4,8,
o:5,7,11,
t:9,14,
n:12,
a:13,
e:15,
so now all I have to do is strip the railing ','