Related
I have an array which looks like
var arr = ["a|c", "a|e", "x|z"];
for(var x in arr){
var appsplit = x.split("|");
}
If the first value(ex: a) in the elements matches then it should combine the values
Ex: output
ace
xz
Please advice how this approach can be done.
You are testing everyone's reading comprehension with that riddle.
var pairs = {};
var arr = ["a|c", "a|e", "x|z"];
for(var x in arr)
{
var appsplit = arr[x].split("|");
if(pairs[appsplit[0]] !== "undefined")
{
pairs[appsplit[0]] = pairs[appsplit[0]] + appsplit[1];
}
else
{
pairs[appsplit[0]] = appsplit[1];
}
}
var matches = [];
for(var x in pairs)
{
matches.push(x + pairs[x]);
}
console.log(matches);
We need to map out the arr elements in this object called pairs. The first value in your split would be the key and the second value is appended (or assigned if it's the first match to the key)
You made an error of splitting x, but you are only splitting the index of the element, not the actual value of the element. arr[x] is the actual value, where x specifies the index in the array.
After we've gone through your arr, we can now merge the key with the values. Your output is contained in matches where the key in each pair is prepended to the value of the key's pair.
Some simple code that would to the trick here.
var arr = ["a|c", "a|e", "x|z", "c|b", "z|e", "c|a"];
var resultObj = {};
arr.forEach(function(element, index){
var array = element.split('|');
if(array.length!==2){
console.log("skipping, invalid input data", element);
} else {
var firstLetter = array[0];
var secondLetter = array[1];
if(resultObj[firstLetter]){
resultObj[firstLetter].push(secondLetter);
} else {
resultObj[firstLetter]=[secondLetter];
}
}
});
Object.keys(resultObj).forEach(function(key){
console.log(key + "," + resultObj[key]);
});
You can use .reduce(), Set to not accumulate duplicate values, .some() to check if previous array contains value in current array, .map(), Array.from() and .join() to convert array to string
var arr = ["a|c", "a|e", "x|z"];
var res = arr.reduce(function(a, b) {
var curr = b.split("|");
var set = new Set;
for (let prop of curr) set.add(prop);
if (!a.length) {
a.push(set)
} else {
for (prop of a) {
if (curr.some(function(el) {
return prop.has(el)
})) {
for (el of curr) {
prop.add(el)
}
} else {
for (let prop of curr) set.add(prop);
a.push(set)
}
}
}
return a
}, []).map(function(m) {
return Array.from([...m], function(el) {
return el
}).join("")
});
console.log(res);
I feel like this can be done more elegantly, but I didn't have time to streamline it. :) The below code will do what you want, though:
var aStartArray = **ARRAY_VALUE_HERE**;
var aSplitResultStrings = [];
// step through each element in the array
for (var i = 0, iSALength = aStartArray.length; i < iSALength; i++) {
// split the values for the current array element
var aSplitVal = aStartArray[i].split("|");
var bStringDoesNotExist = true;
// loop through the "result strings" array
for (var j = 0, iSRSLength = aSplitResultStrings.length; j < iSRSLength; j++) {
// if the first letter from the array element = the first letter of the current "result string" . . .
if (aSplitResultStrings[j].charAt(0) === aSplitVal[0]) {
// append the second letter of the array value to the current result string
aSplitResultStrings[j] = aSplitResultStrings[j] + aSplitVal[1];
// indicate that a match has been found and exit the "result string" loop
bStringDoesNotExist = false;
break;
}
}
// if there are no result strings that start with the first letter of the array value . . .
if (bStringDoesNotExist) {
// concatenate the two values in the current array value and add them as a new "result string"
aSplitResultStrings.push(aSplitVal[0] + aSplitVal[1]);
}
}
Using these arrays, the results are:
aStartArray = ["a|c", "a|e", "x|z"] //results in:
aSplitResultStrings = ["ace", "xz"]
aStartArray = ["a|b", "a|c", "a|d", "a|e", "x|y", "x|z"] //results in:
aSplitResultStrings = ["abcde", "xyz"]
aStartArray = ["a|b", "d|e", "d|f", "x|y", "g|h", "g|i", "m|n", "g|j", "a|c", "x|z"] //results in:
aSplitResultStrings = ["abc", "def", "xyz", "ghij", "mn"]
As I said, this could be more elegant (for example, you could probably use Map to make iterating through the "result strings" easier), but this makes the steps pretty clear and should get you going down the right path towards a final solution.
Given an array of words, write a function that returns an array of the words that occur an even number of times.
function even(["hello", "hi", "hello", "elephant", "hi"]);
That output should be:
["hello", "hi"]
This has been a toy problem I have been struggling with recently. I have solved similar problems counting and returning the number of occurrences of elements in an array but am having trouble taking that logic and applying it to this problem.
This is what I have tried so far, but have hit a wall when trying to output just the even occurrences:
function even(collection) {
var results = [];
for(var i = 0; i < collection.length; i++){
var value = collection[i];
if(results[value]){
results[value] = results[value] + 1;
}else{
results[value] = 1;
}
}
return results;
}
You can use reduce to get an actual count of the words, then simply return an array of the ones that have an even count:
function even(wordsArr) {
//Object of words and counts
var wordCounts = wordsArr.reduce(function(counts, word) {
if (!counts.hasOwnProperty(word)) {
counts[word] = 0;
}
counts[word]++;
return counts;
}, {});
//Now filter that out and return
return Object.keys(wordCounts).filter(function(word) {
return wordCounts[word] % 2 === 0
});
}
even(["hello", "hi", "hello", "elephant", "hi"]); //["hello", "hi"]
var arr = ["hello", "hi", "hello", "elephant", "hi"];
function onlyEvens( arr )
{
var countObj = {};
for( var i = 0; i < arr.length; i++ )
{
var item = arr[i];
if( countObj[ item ] !== undefined )
countObj[item]++;
else
countObj[item] = 1;
}//for()
var filteredArray = [];
for(var key in countObj )
{
if( countObj[key] % 2 == 0 )
filteredArray.push( key );
}
return filteredArray;
}//onlyEvens()
console.log( onlyEvens( arr ) );
Issues in your code:
you use collection instead of words
you cannot access array the associative way. You must declare it as object:
results[value]
you return result variable, but it is undeclared.
return result;
results only contains the occurrences of every word. There miss the code that calculates if the occurrences of a word are odd or even.
fixed code:
function even(words) { // <<< in your code was collection
var results = {};
for(var i = 0; i < words.length; i++){
var value = words[i];
if(results[value]){
results[value] = results[value] + 1;
}else{
results[value] = 1;
}
}
var ret = [];
for(var word in results)
if(results[word]%2 !== 0)
rest.push(word);
return ret;
}
function even(list) {
var d = list.reduce(function(d, w) { d[w] = !d[w]; return d; }, {});
return Object.keys(d).filter(function(w) { return !d[w]; });
}
console.log(even(["hello", "hi", "hello", "elephant", "hi"]));
console.log(even(["hello", "yo", "yo", "hi", "hello", "yo", "elephant", "hi"]));
Explanation: Use the array .reduce() method to create an object (d) with a property for each word (w) with a boolean value indicating whether the word has an odd number of occurrences. Then .filter() the keys to get all the ones that are not odd.
If you previously sort the array you can filter it as required in just a code line like this :
var even = (str) => str.sort().filter((element, index, arr) => index+1 === arr.lastIndexOf(element));
console.log(even(["hello", "hello", "hi", "elephant", "hi", "hi"])); //[ 'hello', 'hi' ]
Here is my javascript array:
arr = ['blue-dots', 'blue', 'red-dots', 'orange-dots', 'blue-dots'];
With Javascript, how can I count the total number of all unique values in the array that contain the string “dots”. So, for the above array the answer would be 3 (blue-dots, orange-dots, and red-dots).
var count = 0,
arr1 = [];
for (var i = 0; i < arr.length; i++) {
if (arr[i].indexOf('dots') !== -1) {
if (arr1.indexOf(arr[i]) === -1) {
count++;
arr1.push(arr[i]);
}
}
}
you check if a certain element contains 'dots', and if it does, you check if it is already in arr1, if not increment count and add element to arr1.
One way is to store element as key of an object, then get the count of the keys:
var arr = ["blue-dots", "blue", "red-dots", "orange-dots", "blue-dots"];
console.log(Object.keys(arr.reduce(function(o, x) {
if (x.indexOf('dots') != -1) {
o[x] = true;
}
return o
}, {})).length)
Try this something like this:
// Create a custom function
function countDots(array) {
var count = 0;
// Get and store each value, so they are not repeated if present.
var uniq_array = [];
array.forEach(function(value) {
if(uniq_array.indexOf(value) == -1) {
uniq_array.push(value);
// Add one to count if 'dots' word is present.
if(value.indexOf('dots') != -1) {
count += 1;
}
}
});
return count;
}
// This will print '3' on console
console.log( countDots(['blue-dots', 'blue', 'red-dots', 'orange-dots', 'blue-dots']) );
From this question, I got the getUnique function.
Array.prototype.getUnique = function(){
var u = {}, a = [];
for(var i = 0, l = this.length; i < l; ++i){
if(u.hasOwnProperty(this[i])) {
continue;
}
a.push(this[i]);
u[this[i]] = 1;
}
return a;
}
then you can add a function that counts ocurrences of a string inside an array of strings:
function getOcurrencesInStrings(targetString, arrayOfStrings){
var ocurrencesCount = 0;
for(var i = 0, arrayOfStrings.length; i++){
if(arrayOfStrings[i].indexOf(targetString) > -1){
ocurrencesCount++;
}
}
return ocurrencesCount;
}
then you just:
getOcurrencesInStrings('dots', initialArray.getUnique())
This will return the number you want.
It's not the smallest piece of code, but It's highly reusable.
var uniqueHolder = {};
var arr = ["blue-dots", "blue", "red-dots", "orange-dots", "blue-dots"];
arr.filter(function(item) {
return item.indexOf('dots') > -1;
})
.forEach(function(item) {
uniqueHolder[item] ? void(0) : uniqueHolder[item] = true;
});
console.log('Count: ' + Object.keys(uniqueHolder).length);
console.log('Values: ' + Object.keys(uniqueHolder));
Try this code,
arr = ["blue-dots", "blue", "red-dots", "orange-dots", "blue-dots"];
sample = [];
for (var i = 0; i < arr.length; i++) {
if ((arr[i].indexOf('dots') !== -1) && (sample.indexOf(arr[i]) === -1)){
sample.push(arr[i]);
}
}
alert(sample.length);
var arr = [ "blue-dots", "blue", "red-dots", "orange-dots", "blue-dots" ];
var fArr = []; // Empty array, which could replace arr after the filtering is done.
arr.forEach( function( v ) {
v.indexOf( "dots" ) > -1 && fArr.indexOf( v ) === -1 ? fArr.push( v ) : null;
// Filter if "dots" is in the string, and not already in the other array.
});
// Code for displaying result on page, not necessary to filter arr
document.querySelector( ".before" ).innerHTML = arr.join( ", " );
document.querySelector( ".after" ).innerHTML = fArr.join( ", " );
Before:
<pre class="before">
</pre>
After:
<pre class="after">
</pre>
To put this simply, it will loop through the array, and if dots is in the string, AND it doesn't already exist in fArr, it'll push it into fArr, otherwise it'll do nothing.
I'd separate the operations of string comparison and returning unique items, to make your code easier to test, read, and reuse.
var unique = function(a){
return a.length === 0 ? [] : [a[0]].concat(unique(a.filter(function(x){
return x !== a[0];
})));
};
var has = function(x){
return function(y){
return y.indexOf(x) !== -1;
};
};
var arr = ["blue-dots", "blue", "red-dots", "orange-dots", "blue-dots"];
var uniquedots = unique(arr.filter(has('dots')));
console.log(uniquedots);
console.log(uniquedots.length);
I'm receiving a String like this:
"45,21,555,64,94,796,488,\n " the \n means new line
is there a way to cut the string based on "," and getting only the "number".
I could do it C but how can I search for a character in JavaScript.
thanks for any hint
var parts = "45,21,555,64,94,796,488,\n ".split(',').filter(function(val) {
var num = parseInt(val, 10);
return !isNaN(num) && toString.call(num) === '[object Number]';
});
// parts: ["45", "21", "555", "64", "94", "796", "488"]
This is taking your String and splitting it into an Array based on a delimiter (',') and then running it through a filter function to remove anything that does not evaluate to a valid Number.
See String.prototype.split and Array.prototype.filter.
If you actually want to then convert those values to Numbers, you could chain a map call:
var parts = "45,21,555,64,94,796,488,\n ".split(',')
.filter(function(val) {
var num = parseInt(val, 10);
return !isNaN(num) && toString.call(num) === '[object Number]';
})
.map(function(val) {
return parseInt(val, 10);
});
// parts: [45, 21, 555, 64, 94, 796, 488]
Yes, like this:
var myString = "45,21,555,64,94,796,488,\n ";
var splitStrings = string.split(",");
console.log(splitStrings); //Should log an array to the console, containing only your strings e.g. [45,21,555,64,94,796,488,\n]
This returns an array of strings, split by the character you passed in. You can read more on this method here: http://www.w3schools.com/jsref/jsref_split.asp
After that, you can parse your array to remove anything you don't want like the new line character, or use a filter method to do it inline as detailed in another answer
You can use string.split(splitChar) to split. Then you can use .map or .filter to convert items to number.
var str = "45,21,555,64,94,796,488,\n ";
var arr = str.split(",");
document.write("Array: <pre>"+JSON.stringify(arr)+"</pre>");
var nums = arr.map(function(item){
return parseInt(item);
});
document.write("Numbers: <pre>"+JSON.stringify(nums)+"</pre>");
If you are wanting just the numbers as an array you could do this.
var str = "45,21,555,64,94,796,488,\n ";
var arr = str.split(","); //Make the string into an array
var len = arr.length;
for(var i=0;i<len;i++)
{
try
{
arr[i] = parseInt(arr[i]); // convert the numbers to ints
}
catch(e)
{
arr[i] = null;
}
}
As the fact that strings are just arrays, you can do it this way (a bit more comprehensive, in my opinion):
function noCommas(a)
{
var b = '';
for (var i = 0; i < a.length; i++)
{
if (a[i] != ',') //&& a[i]!= String.fromCharCode(10)) If you want no new lines too
{
b += a[i];
} else
{
//break; -> In case you only want the first value
}
}
return parseInt(b); //To return the value as an integer
}
noCommas('1234,6789'); // returns 12346789
I missunderstood the question, so here's my fixed code:
function noCommas(a)
{
var b = [];
var tempNum = '';
for (var i = 0; i < a.length; i++)
{
if (a[i] != ',' && i != a.length - 1)
{
tempNum += a[i];
} else
{
b.push(parseInt(tempNum))
tempNum = '';
}
}
return b;
}
now if you do noCommas('123,345,324234')[2] it would return 324234.
I'm trying to loop thru a string with numbers that has a symbol inside, I want the numbers before the symbol to be pushed to an array then the symbol to another array and then get the rest of the numbers after the symbol pushed to a 3rd array.
var myString = "1234*5678";
var number1 = [];
for (i = 0; i < myString.length; i++) {
if (isNaN(myString[i]) === false) {
var firstSet = number1.push(myString[i]);
}
};
var mySymbol = [];
for (j = number1[0]; j < myString.length; j++) {
if (isNaN(myString[j]) === true) {
var mathematics = mySymbol.push(myString[j])
document.write(mySymbol[0])
}
};
when I document.write the "mySymbol" variable it gives the desired result, but when I call the "number1" variable it gives me the numbers from before and after the symbol I only want the numbers before the symbol to be pushed to the array, also how do I write the 3rd loop to get the numbers after the symbol pushed to a new array?
try
var arr=[[],[],[]]
index = 0
"1234*5678".split('').forEach(function(e){
if(parseInt(e)){
arr[index].push(e);
}else{
index ++;
arr[index++].push(e)
}
});
document.write('First Array ' +arr[0] + '<br>');
document.write('Secont Array ' +arr[1] + '<br>');
document.write('Third Array ' +arr[2]);
You could try using:
var myString = '1234*5678';
var resultArr = myString.match(/([a-zA-Z0-9]+)([^a-zA-Z0-9])([a-zA-Z0-9]+)/);
To get the string before symbol:
var myFirstSet = resultArr[1];
To get symbol:
var mySymbol = resultArr[2];
To get the string after symbol:
var mySecondSet = resultArr[3];
To convert each of these three groups into their own arrays:
var result = [];
resultArr
.slice(1)
.forEach(
function(s){
result.push(s
.split('')
.map(
function(n){
return parseInt(n) || n;
}
)
)
}
);
The following code accomplishes the goal:
var str = '1234*5678';
var arr = str.match(/([a-zA-Z0-9]+)|\*/g);
console.log(arr[0], arr[1], arr[2]);
http://jsfiddle.net/hp2ohvzb/