I have two arrays
var arr1 = ['wq','qw','qq'];
var arr2 = ['wq','wq','wq','qw','qw','qw','qw','qq','qq'];
Below what i did is matching arr1 values with arr2. If the array contains same values i pushed the values into newArr.
var newArr = [];
for (var i=0;i<arr1.length;i++) {
newArr[i] = [];
}
for (var i=0;i<arr2.length;i++) {
for (var j=0;j<arr1.length;j++) {
if (arr2[i].indexOf(arr1[j]) != -1)
newArr[j].push(arr2[i]);
}
}
console.log(newArr[1]); //newArr[0] = ['wq','wq','wq'];//In second output array newArr[1] = ['qw','qw','qw','qw'];
Is there any easy way to solve this without using two for loops. Better i need a solution in javascript
Maybe use indexOf():
var count = 0;
for (var i = 0; i < arr1.length; i++) {
if (arr2.indexOf(arr1[i]) != -1) {
count++;
// if you just need a value to be present in both arrays to add it
// to the new array, then you can do it here
// arr1[i] will be in both arrays if you enter this if clause
}
}
if (count == arr1.length) {
// all array 1 values are present in array 2
} else {
// some or all values of array 1 are not present in array 2
}
Your own way wasn't totally wrong, you just had to check if the element was index of the array and not of an element in the array.
var arr1 = ['wq','qw','qq'];
var arr2 = ['wq','wq','wq','qw','qw','qw','qw','qq','qq'];
var newArr = [];
for (var i in arr1) {
newArr[i] = [];
}
for (var i in arr2) {
var j = arr1.indexOf(arr2[i]);
if (j != -1) {
newArr[j].push(arr2[i]);
}
}
This way you removed the nested for loop and it still gives you the result you asked for.
var arr1 = ['wq','qw','qq','pppp'];
var arr2 = ['wq','wq','wq','qw','qw','qw','qw','qq','qq'];
function intersect(a, b) {
var d = {};
var results = [];
for (var i = 0; i
d[b[i]] = true;
}
for (var j = 0; j
if (d[a[j]])
results.push(a[j]);
}
return results;
}
var result_array = intersect(arr1,arr2);
// result_array will be like you want ['wq','wq','wq'];
Related
I want to count how often a number in an Array occurs. For example, in Python I can use Collections.Counter to create a dictionary of how frequently an item occurs in a list.
This is as far as I've gotten in JavaScript:
var array = [1,4,4,5,5,7];
var obj = {};
for (var i=0; i < array.length; i++) {
/* obj[array[i]] = +=1 */ <= pseudo code
}
How can I create this frequency counter object?
Close but you can't increment undefined so you need to set initial value if it doesn't exist
var array = [1,4,4,5,5,7];
var obj = {};
for (var i=0; i < array.length; i++) {
obj[array[i]] = (obj[array[i]] || 0) +1 ;
}
You were almost there. See below code:
var array = [1,4,4,5,5,7];
var obj = {};
for (var i=0; i < array.length; i++) {
obj[array[i]] = (obj[array[i]] || 0 ) +1;
}
console.log(obj);
Create an object and check if that specific key exist.If exist then increase it's value by 1
var array = [1, 4, 4, 5, 5, 7];
var obj = {};
for (var i = 0; i < array.length; i++) {
if (obj.hasOwnProperty(array[i])) {
obj[array[i]] += 1;
} else {
obj[array[i]] = 1;
}
}
console.log(obj)
You can use the ? : ternary operator to set initial value as 1 and then increment it on subsequent matches.
var array = [1,4,4,5,5,7];
var obj = {};
for (var i=0; i < array.length; i++) {
obj[array[i]] = obj[array[i]]?obj[array[i]]+1:1;
}
console.log(obj);
If the array is always going to be same, and you are going to check frequency of multiple items in the same array without it it being modified, #JohanP's answer is good.
But if you are only going to check frequency of only one item, or the array can change, creating the object is nothing but extra overhead.
In that case, you can do something like this:
const getItemFrequency = function(array, item) {
return array.filter(i => i === item).length;
}
var array = [1,4,4,5,5,7];
console.log(getItemFrequency(array, 4));
Concise logic written as proper function:
function countArrayItemFrequecy(array) {
const length = array.length;
const map = {};
for ( let i = 0; i < length; i++ ) {
let currentItem = array[i];
if (typeof map[currentItem] !== 'undefined' ) {
map[currentItem]++
} else {
map[currentItem] = 1
}
}
return map;
}
You need to make sure to assign default value to your frequency object for the first occurrence of the item. As a shortcut you can use ternary operator
var array = [1,4,4,5,5,7];
var obj = {};
for (var i=0; i < array.length; i++) {
obj[array[i]] = obj[array[i]] ? obj[array[i]]++ : 1;
}
which is the same as:
var array = [1,4,4,5,5,7];
var obj = {};
for (var i=0; i < array.length; i++) {
if (obj[array[i]]) {
obj[array[i]]++;
} else {
obj[array[i]] = 1;
}
}
You can use Object.assign: below clones map and then increments/adds the counter. These are pure (no side effects/param reassignment), single-purpose functions.
addToMap does the same thing as { ...map, map[e]: [e]: (map[e] || 0) + 1 }, but that requires babel.
const addToMap = (map, e) => Object.assign({}, map, { [e]: (map[e] || 0) + 1 });
const buildMap = a => a.reduce(addToMap, {});
Using Array.reduce:
arr.reduce(function (acc, item) {
acc[item] = (acc[item] || 0) + 1;
return acc;
}, {});
Example:
var arr = [1,1,2,4,1,4];
var counts = arr.reduce(function (acc, item) {
acc[item] = (acc[item] || 0) + 1;
return acc;
}, {});
console.log(counts);
First of all thank you to whoever reads this whole question. I am having trouble writing a function that can take a key array and use the indices to remove like items from a main array.
My main Array
var mainArray = [
{fruit:"apple",color:"red"},
{fruit:"orange",color:"orange"},
{fruit:"banana",color:"yellow"},
{fruit:"apple",color:"red"},
{fruit:"banana",color:"yellow"},
{fruit:"mango",color:"greenishyellowishred"}
]
Array of items will be added to this mainArray and I need to remove multiple items at a time.
My key Array
var keyArray = [{fruit:"apple",color:"red"}, {fruit:"banana",color:"yellow"}]
I am attempting to remove the "apple" and the "banana" by using a for loop to decrement through the array to maintain the integrity of the mainArray.
for(var i = mainArray.length - 1; i > -1; i--) {
for(var j = keyArray.length - 1; j > -1; j--) {
if(mainArray[i].fruit === keyArray[j].fruit) {
mainArray.splice(i, 1)
keyArray.splice(j, 1)
}
}
}
My issue comes when I am trying to read mainArray[i].fruit if i = 0
Thanks in advance for any help possible.
Try the following way:
var mainArray = [
{fruit:"apple",color:"red"},
{fruit:"orange",color:"orange"},
{fruit:"banana",color:"yellow"},
{fruit:"apple",color:"red"},
{fruit:"banana",color:"yellow"},
{fruit:"mango",color:"greenishyellowishred"}
];
var keyArray = [{fruit:"apple",color:"red"}, {fruit:"banana",color:"yellow"}];
var tempArray = [];
for(let j = 0; j < keyArray.length; j++) {
for(let i = 0; i < mainArray.length; i++) {
if(mainArray[i].fruit === keyArray[j].fruit) {
tempArray.push(mainArray[i]);
}
}
}
mainArray = mainArray.filter( function( el ) {
return !tempArray.includes( el );
});
console.log(mainArray);
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);
Hey i have a simple question i cant find an answer,
i´m trying to generate some raw-data for a chart
lets say i have an array like :
[1,0,0,1,2,0]
is there a way to make an array out of it that has nested arrays that represent the count of duplicate entrys ?
[[0,3],[1,2],[2,1]]
here is some code that does the trick, but saves the count as objects
var array = [1,0,0,1,2,0];
var length = array.length;
var objectCounter = {};
for (i = 0; i < length; i++) {
var currentMemboerOfArrayKey = JSON.stringify(array[i]);
var currentMemboerOfArrayValue = array[i];
if (objectCounter[currentMemboerOfArrayKey] === undefined){
objectCounter[currentMemboerOfArrayKey] = 1;
}else{
objectCounter[currentMemboerOfArrayKey]++;
}
}
but objectCounter returns them like
{0:3,1:2,2:1}
but i need it as an array i specified above ?
for any help, thanks in advance
Try
var array = [1, 0, 0, 1, 2, 0];
function counter(array) {
var counter = [],
map = {}, length = array.length;
$.each(array, function (i, val) {
var arr = map[val];
if (!arr) {
map[val] = arr = [val, 0];
counter.push(arr);
}
arr[1] += 1;
})
return counter;
}
console.log(JSON.stringify(counter(array)))
Demo: Fiddle
You can turn your object into an array easily:
var obj = {0:3,1:2,2:1};
var arr = [];
for (var key in obj) {
// optional check against Object.prototype changes
if (obj.hasOwnProperty(key)) {
arr.push([+key, obj[key]]);
}
}
Note: The object keys are strings, so i converted them back to numbers when placed in the array.
Functional way of doing this, with Array.reduce and Array.map
var data = [1,0,0,1,2,0];
var result = data.reduce(function(counts, current) {
counts[current] = current in counts ? counts[current] + 1: 1;
return counts;
}, {});
result = Object.keys(result).map(function(current){
return [parseInt(current), result[current]];
});
console.log(result);
Output
[ [ 0, 3 ], [ 1, 2 ], [ 2, 1 ] ]
Try:
var data = [1,0,0,1,2,0];
var len = data.length;
var ndata = [];
for(var i=0;i<len;i++){
var count = 0;
for(var j=i+1;j<len;j++){
if(data[i] == data[i]){
count ++;
}
}
var a = [];
a.push(data[i]);
a.push(count);
ndata.push(a);
}
console.log(ndata)
DEMO here.
First you need to map the array to an associative object
var arr = [1,0,0,1,2,0];
var obj = {};
for (var i = 0; i < arr.length; i++) {
if (obj[arr[i]] == undefined) {
obj[arr[i]] = 0;
}
obj[arr[i]] += 1;
}
Then you can easily turn that object into a 2d matrix like so:
arr = [];
for (var k in obj) {
arr.push([k, obj[k]]);
}
alert(JSON.stringify(arr));
Your existing object can be turned into an array with a simple for..in loop. Also your existing code that produces that object can be simplified. Encapsulate both parts in a function and you get something like this:
function countArrayValues(array) {
var counter = {},
result = [];
for (var i = 0, len = array.length; i < len; i++)
if (array[i] in counter)
counter[array[i]]++;
else
counter[array[i]] = 1;
for (i in counter)
result.push([+i, counter[i]]);
return result;
}
console.log( countArrayValues([1,0,0,1,2,0]) );
Demo: http://jsfiddle.net/hxRz2/
I have already first column sorted 2D Javascript Array
var arr = [[12.485019620906078, 236.90974767017053|166.7059999999991|244.15878139435978|156.54100000000025],
[12.735148445872, 238.038907254076|203.3000000000006|245.7107245706185|213.46500000000034],
[47.15778769718685, 238.038907254076|203.3000000000006|244.15878139435978|156.54100000000025],
[47.580051233708595, 236.90974767017053|166.7059999999991|245.7107245706185|213.46500000000034]
];
I am trying to remove the duplicates based on the last two values in the [i][1] part of array
244.15878139435978|156.54100000000025
245.7107245706185|213.46500000000034
using following function which is not giving correct output
function remDupes(arr)
{
for(var i=0; i<arr.length-1; i++)
{
var i1 = arr[i][1].split("|");
var item1 = i1[2]+"|"+i1[3];
for(var j=i+1; j<arr.length; j++)
{
var i2 = arr[j][1].split("|");
var item2 = i2[2]+"|"+i2[3];
if(item1 == item2)
{
arr.splice(j,1);
}
}
}
return arr;
}
I am looking for final array like this.
[
[12.485019620906078, 236.90974767017053|166.7059999999991|244.15878139435978|156.54100000000025],
[12.735148445872, 238.038907254076|203.3000000000006|245.7107245706185|213.46500000000034]
]