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Compare 2 arrays and combine in Javascript

How can i compare and combine 2 arrays using array functions of javascript or using lodash?
I have this initial array of dates for last 30 days.
[
'2022-12-11', '2022-12-12', '2022-12-13',
'2022-12-14', '2022-12-15', '2022-12-16',
'2022-12-17', '2022-12-18', '2022-12-19',
'2022-12-20', '2022-12-21', '2022-12-22',
'2022-12-23', '2022-12-24', '2022-12-25',
'2022-12-26', '2022-12-27', '2022-12-28',
'2022-12-29', '2022-12-30', '2022-12-31',
'2023-01-01', '2023-01-02', '2023-01-03',
'2023-01-04', '2023-01-05', '2023-01-06',
'2023-01-07', '2023-01-08', '2023-01-09',
'2023-01-10', '2023-01-11'
]
Then this is the second with count value.
[ [ '2023-01-09', 1 ], [ '2023-01-10', 3 ] ]
Now i have this code that compare and combine these array manually
let testData = [];
let k = 0;
dayList.forEach(o => {
let is_match = 0;
let frags = [];
submitted.forEach(i => {
if(o == i[0]){
is_match = 1;
frags = i;
}
});
testData[k] = [
(is_match == 1) ? frags[0] : o,
(is_match == 1) ? frags[1] : 0
];
k++;
});
console.log(testData);
this will result to...
[
[ '2022-12-11', 0 ], [ '2022-12-12', 0 ],
[ '2022-12-13', 0 ], [ '2022-12-14', 0 ],
[ '2022-12-15', 0 ], [ '2022-12-16', 0 ],
[ '2022-12-17', 0 ], [ '2022-12-18', 0 ],
[ '2022-12-19', 0 ], [ '2022-12-20', 0 ],
[ '2022-12-21', 0 ], [ '2022-12-22', 0 ],
[ '2022-12-23', 0 ], [ '2022-12-24', 0 ],
[ '2022-12-25', 0 ], [ '2022-12-26', 0 ],
[ '2022-12-27', 0 ], [ '2022-12-28', 0 ],
[ '2022-12-29', 0 ], [ '2022-12-30', 0 ],
[ '2022-12-31', 0 ], [ '2023-01-01', 0 ],
[ '2023-01-02', 0 ], [ '2023-01-03', 0 ],
[ '2023-01-04', 0 ], [ '2023-01-05', 0 ],
[ '2023-01-06', 0 ], [ '2023-01-07', 0 ],
[ '2023-01-08', 0 ], [ '2023-01-09', 1 ],
[ '2023-01-10', 3 ], [ '2023-01-11', 0 ]
]
As you can see the date 2023-01-09 and 2023-01-10 have values then the rest has 0 values.
Which is what i expected, i'm just new in coding a pure javascript application, i just translated my PHP code to javascript.
Now is there a way that this code may be simplified using array functions of javascript or using lodash?

Here's an approach, we first create a map with the date as key and count as value and then use this map to generate the result
const dates=["2022-12-11","2022-12-12","2022-12-13","2022-12-14","2022-12-15","2022-12-16","2022-12-17","2022-12-18","2022-12-19","2022-12-20","2022-12-21","2022-12-22","2022-12-23","2022-12-24","2022-12-25","2022-12-26","2022-12-27","2022-12-28","2022-12-29","2022-12-30","2022-12-31","2023-01-01","2023-01-02","2023-01-03","2023-01-04","2023-01-05","2023-01-06","2023-01-07","2023-01-08","2023-01-09","2023-01-10","2023-01-11",];
const count=[["2023-01-09",1],["2023-01-10",3]];
const countMap = count.reduce((acc, [date, count]) => {
acc[date] = count;
return acc;
}, {});
const result = dates.map((date) => [date, countMap[date] || 0]);
console.log(result)

You can simply run any loop and find the index of the current element in the submitted array and check if exist then assign date otherwise assign 0 to the array
var dayList = ['2022-12-11', '2023-01-10', '2023-01-09']
var submitted = [ [ '2023-01-09', 1 ], [ '2023-01-10', 3 ] ]
var testData = []
dayList.filter(o => {
const exist = submitted.find(e => e.indexOf(o) != -1)
if(exist){
testData.push([o, exist[1]])
} else {
testData.push([o, 0])
}
});
console.log("your data=", testData)

How to include zero counts in a javascript frequency counting function for histograms

Need some help please - am using the excellent response to this histogram bucketing question as per code below. My question is what is the most elegant way to get my buckets with zero counts represented in the function output?
Current Output is:
[ [ '0', 2 ],
[ '32', 1 ],
[ '64', 2 ],
[ '80', 1 ],
[ '96', 1 ],
[ '112', 1 ] ]
which omits to note buckets 16 and 48 which have zero counts.
My desired output is:
[ [ '0', 2 ],
[ '16', 0 ],
[ '32', 1 ],
[ '48', 0 ],
[ '64', 2 ],
[ '80', 1 ],
[ '96', 1 ],
[ '112', 1 ] ]
All help much appreciated.
function defArrs (){
var arr = [1,16,38,65,78,94,105,124]
var binsize = 16;
var check = Object.entries(frequencies (arr,binsize));
console.log(check);
}
function frequencies(values, binsize) {
var mapped = values.map(function(val) {
return Math.ceil(val / binsize) -1;
});
console.log(mapped);
return mapped.reduce(function (freqs, val, i) {
var bin = (binsize * val);
freqs[bin] ? freqs[bin]++ : freqs[bin] = 1;
return freqs;
}, {});
}

Instead of starting with the empty object for .reduce:
}, {});
// ^^
construct one with all the properties you'll want to be included at the end (starting with a count of 0, of course).
const initialObj = Object.fromEntries(
Array.from(
{ length: 7 },
(_, i) => [i * binsize, 0]
)
);
And pass that as the second parameter to .reduce.
That approach also means that this
freqs[bin] ? freqs[bin]++ : freqs[bin] = 1;
will simplify to
freqs[bin]++;
Or, even better:
const frequencies = (nums, binsize) => {
const mapped = nums.map(num => Math.ceil(num / binsize) - 1;
const grouped = Object.fromEntries(
{ length: 7 },
(_, i) => [i * binsize, 0]
);
for (const val of mapped) {
grouped[binsize * val]++;
}
return grouped;
};

Function on a nested array in js

Here is my Function which turns timestamps to seconds,
const convertor = (x) => {
const result = x.split(':');
const final =
parseInt(result[0] * 60) +
parseInt(result[1] * 60) +
parseInt(result[2]) -
1.2;
return final;
};
input = 00:01:02.330
result: 62.330
How can I implement it on a nested array like this?
array = [ [ 00:01:02.330],[00:01:04.550],[01:11:02.330] ], [ [00:01:02.330],[00:01:02.330] ] , [ [00:01:02.330],[00:01:02.330],[00:01:02.330] ] ]
I want to preserve its nested structure so the result should be:
[ [ 22.3],[28.5],[903.50] ], [ [1252.3],[62.2] ] , [ [654.25],[965.25],[1254.32] ] ]

You can write a wrapper that accepts a function and an array, and maps over the array-- if the item is an array, it recurses; otherwise, it passes the item into the passed function-- this allows you to process nested arrays of any arbitrary depth and retain the desired structure:
const convertor = (x) => {
const result = x.split(':');
const final =
parseInt(result[0] * 60) +
parseInt(result[1] * 60) +
parseInt(result[2]) -
1.2;
return final;
};
const recursiveNestedMapper = (fn, arr) => {
const output = arr.map((item) => {
if (Array.isArray(item)) {
return recursiveNestedMapper(fn, item);
} else {
return fn(item);
}
});
return output;
}
const inputArray = [
[
['00:01:02.330'],
['00:01:04.550'],
['01:11:02.330']
],
[
['00:01:02.330'],
['00:01:02.330']
],
[
['00:01:02.330'],
['00:01:02.330'],
['00:01:02.330']
]
];
const outArray = recursiveNestedMapper(convertor, inputArray);
console.log(outArray);

Not sure why you're keeping the timestamps in an array when it's the only element, but you can get the desired output by chaining map()
const convertor = (x) => {
const result = x[0].split(':');
const final =
parseInt(result[0] * 60) +
parseInt(result[1] * 60) +
parseInt(result[2]) -
1.2;
return final;
};
const array = [
[ [ '00:01:02.330' ], [ '00:01:04.550' ], [ '01:11:02.330' ] ],
[ [ '00:01:02.330' ], [ '00:01:02.330' ] ],
[ [ '00:01:02.330' ], [ '00:01:02.330' ], [ '00:01:02.330' ] ]
];
const output = array.map(a => a.map(b => convertor(b)));
console.log(output);
[
[
60.8,
62.8,
720.8
],
[
60.8,
60.8
],
[
60.8,
60.8,
60.8
]
]

Javascript: update a column in matrix

I want to update an entire column of a matrix.
I started by initializing the matrix like:
m =({length:10}, (_,i) => Array.from({length:2}, (_,j) => i+'x'+j));
Then, I have an array of 2 element (say, a2) that I want to put in the j-th column of the matrix with manipulation.
If I am using matlab I would do the following: m(:,j)=a2+ m(:,j)
How can I do this in javascript?

Do you mean like this?:
const m = Array.from({length:10}, (_,i) => Array.from({length:2}, (_,j) => i+'x'+j));
console.log("before", m);
const j = 2;
const a2 = "z"
const n = m.map(row => {row.splice(j, 0, a2); return row});
console.log("after", n);
before manipulation:
before [
[ "0x0", "0x1" ],
[ "1x0", "1x1" ],
[ "2x0", "2x1" ],
[ "3x0", "3x1" ],
[ "4x0", "4x1" ],
[ "5x0", "5x1" ],
[ "6x0", "6x1" ],
[ "7x0", "7x1" ],
[ "8x0", "8x1" ],
[ "9x0", "9x1" ]
]
And after manipulation (i.e. add "z" to column 2):
after [
[ "0x0", "0x1", "z" ],
[ "1x0", "1x1", "z" ],
[ "2x0", "2x1", "z" ],
[ "3x0", "3x1", "z" ],
[ "4x0", "4x1", "z" ],
[ "5x0", "5x1", "z" ],
[ "6x0", "6x1", "z" ],
[ "7x0", "7x1", "z" ],
[ "8x0", "8x1", "z" ],
[ "9x0", "9x1", "z" ]
]
Or if a2 should be an array itself? Then, the simple case that it is a 1D array:
const m = Array.from({length:10}, (_,i) => Array.from({length:2}, (_,j) => i+'x'+j));
console.log("before", m);
const j = 2;
const a2 = Array.from({length:10}, (_,j) => 'z'+j)
const n = m.map((row, i) => {row.splice(j, 0, a2[i]); return row});
console.log("after", n);
After manipulation (i.e. add "z{ i }" to column 2):
after [
[ "0x0", "0x1", "z0" ],
[ "1x0", "1x1", "z1" ],
[ "2x0", "2x1", "z2" ],
[ "3x0", "3x1", "z3" ],
[ "4x0", "4x1", "z4" ],
[ "5x0", "5x1", "z5" ],
[ "6x0", "6x1", "z6" ],
[ "7x0", "7x1", "z7" ],
[ "8x0", "8x1", "z8" ],
[ "9x0", "9x1", "z9" ]
]
Or the more complex case when a2 is a 2D array:
const m = Array.from({length:10}, (_,i) => Array.from({length:2}, (_,j) => i+'x'+j));
console.log("before", m);
const j = 2;
const a2 = Array.from({length:10}, (_,i) => Array.from({length:2}, (_,j) => i+'z'+j));
const n = m.map((row, i) => {row.splice(j, 0, a2[i]); return row.flat()});
console.log("after", n);
After manipulation (i.e. add "z{ i }" to column 2):
after [
[ "0x0", "0x1", "0z0", "0z1" ],
[ "1x0", "1x1", "1z0", "1z1" ],
[ "2x0", "2x1", "2z0", "2z1" ],
[ "3x0", "3x1", "3z0", "3z1" ],
[ "4x0", "4x1", "4z0", "4z1" ],
[ "5x0", "5x1", "5z0", "5z1" ],
[ "6x0", "6x1", "6z0", "6z1" ],
[ "7x0", "7x1", "7z0", "7z1" ],
[ "8x0", "8x1", "8z0", "8z1" ],
[ "9x0", "9x1", "9z0", "9z1" ]
]

I think using Array.prototype.forEach and Array.prototype.splice is a good way to accomplish this:
// Setup for demo
const Row = (w) =>Array.from({length:w}).fill('').map((c,i)=>c=i);
const Matrix = (h, w) => Array.from({length:h}).fill('').map(r=>r=Row(w));
const print = (mtx) => mtx.forEach(r=>console.log([...r].join(", ")));
// Original state of matrix
const m1 = Matrix(2,10);
print(m1);
console.log('----------');
// Insertion function
const insertCol = (mtx, cInd, newCol) => {
mtx.forEach( (row, rInd) => { row.splice(cInd, 0, newCol[rInd]); }
);
}
// Matrix with inserted column
const someCol = ['X','Y'];
insertCol(m1, 3, someCol);
print(m1);

Separate string by numbers and characters

I am trying to format a string to produce a new string in the correct format:
I have the following strings (left) which should be formatted to match (right):
[ 'xx9999', 'XX-99-99' ],
[ '9999xx', '99-99-XX' ],
[ '99xx99', '99-XX-99' ],
[ 'xx99xx', 'XX-99-XX' ],
[ 'xxxx99', 'XX-XX-99' ],
[ '99xxxx', '99-XX-XX' ],
[ '99xxx9', '99-XXX-9' ],
[ '9xxx99', '9-XXX-99' ],
[ 'xx999x', 'XX-999-X' ],
[ 'x999xx', 'X-999-XX' ],
[ 'xxx99x', 'XXX-99-X' ],
[ 'x99xxx', 'X-99-XXX' ],
[ '9xx999', '9-XX-999' ],
[ '999xx9', '999-XX-9' ]
I have tried the following but cannot get it to work correctly:
const formatLp = (userInput) => {
if (userInput) {
return userInput.toUpperCase().match(/[a-z]+|[^a-z]+/gi).join('-');
}
}
This works for some of them, such as 99xxx9 but not others such as xx9999
any help would be appreciated.

Use .replace twice - once to insert a - between 4 repeated digits/non-digits, and once to insert a - between digits and alphabetical characters:
const arr = [
[ 'xx9999', 'XX-99-99' ],
[ '9999xx', '99-99-XX' ],
[ '99xx99', '99-XX-99' ],
[ 'xx99xx', 'XX-99-XX' ],
[ 'xxxx99', 'XX-XX-99' ],
[ '99xxxx', '99-XX-XX' ],
[ '99xxx9', '99-XXX-9' ],
[ '9xxx99', '9-XXX-99' ],
[ 'xx999x', 'XX-999-X' ],
[ 'x999xx', 'X-999-XX' ],
[ 'xxx99x', 'XXX-99-X' ],
[ 'x99xxx', 'X-99-XXX' ],
[ '9xx999', '9-XX-999' ],
[ '999xx9', '999-XX-9' ]
];
arr.forEach(([str]) => {
const result = str.toUpperCase()
.replace(/\d{4}|\D{4}/, substr => `${substr.slice(0, 2)}-${substr.slice(2)}`)
.replace(/[a-z]{4}|\d(?=[a-z])|[a-z](?=\d)/gi, '$&-');
console.log(result);
});
You can also do it by matching and then joining - match 3 non-digits, or 3 digits, or 1-2 non-digits, or 1-2 digits:
const arr = [
[ 'xx9999', 'XX-99-99' ],
[ '9999xx', '99-99-XX' ],
[ '99xx99', '99-XX-99' ],
[ 'xx99xx', 'XX-99-XX' ],
[ 'xxxx99', 'XX-XX-99' ],
[ '99xxxx', '99-XX-XX' ],
[ '99xxx9', '99-XXX-9' ],
[ '9xxx99', '9-XXX-99' ],
[ 'xx999x', 'XX-999-X' ],
[ 'x999xx', 'X-999-XX' ],
[ 'xxx99x', 'XXX-99-X' ],
[ 'x99xxx', 'X-99-XXX' ],
[ '9xx999', '9-XX-999' ],
[ '999xx9', '999-XX-9' ]
];
arr.forEach(([str]) => {
const result = str.toUpperCase()
.match(/[a-z]{3}|\d{3}|[a-z]{1,2}|\d{1,2}/gi)
.join('-');
console.log(result);
});

I've just implemented this using Stack. Here is the function. You just need to pass the string to this function.
const convert = (str) => {
let stack = str.split('').reduce((newArr, char, index) => {
if(index !== 0 && newArr[newArr.length-1] !== char) {
newArr.push('-');
newArr.push(char);
return newArr;
} else {
newArr.push(char);
return newArr;
}
},[])
return stack.join('').toUpperCase();
}
// Here you can check this in action
const convert = (str) => {
let stack = str.split('').reduce((newArr, char, index) => {
if(index !== 0 && newArr[newArr.length-1] !== char) {
newArr.push('-');
newArr.push(char);
return newArr;
} else {
newArr.push(char);
return newArr;
}
},[])
return stack.join('').toUpperCase();
}
const strings = [ 'xx9999','9999xx','99xx99','xx99xx','xxxx99','99xxxx','99xxx9','9xxx99','xx999x','x999xx','xxx99x','x99xxx','9xx999','999xx9',];
strings.map(string => console.log(convert(string)))