Shuffle not JavaScript array!

Question

Shuffle not JavaScript array!

After extracting data from PDF files, I found myself with a vast array of information. Each PDF page contained 10 data items arranged in two columns, causing the data to be shuffled. While the first and last items were correctly positioned within each group of ten, the rest were mixed up.

Currently, the order of the data is 0, 2, 4, 6, 8, 1, 3, 5, 7, 9, 10, 12, 14, 16, 18, 11... but I require it to be in sequential order starting from 0, 1, 2, 3...

I have attempted to iterate through the array and transfer items into a new array using various if statements, yet I seem unable to achieve the desired outcome.

javascript arrays algorithm sorting

Answer 1

Answer №1

Presented below is a function designed to handle incoming data along with two additional parameters specifying the number of columns and rows on a page:

function uncolumnize(data, numColumns, numRows) {
    let perPage = numColumns * numRows;
    return data.map((_, i) =>
        data[Math.floor(i / perPage) * perPage 
           + Math.floor((i % perPage) / numColumns) 
           + (i % numColumns) * numRows]
    );
}

let result = uncolumnize([0,2,4,6,8,1,3,5,7,9,10,12,14,16,18,11,13,15,17,19], 2, 5);
console.log(result);

This implementation utilizes the map Array method as the resulting array will have the same length as the original data. The callback specified for map only relies on the index rather than the value itself. This index assists in determining the page, row, and column information. By rearranging the row and column values, a new index is constructed which then retrieves the corresponding data.

Answer 2

Presented below is a function designed to handle incoming data along with two additional parameters specifying the number of columns and rows on a page:

function uncolumnize(data, numColumns, numRows) {
    let perPage = numColumns * numRows;
    return data.map((_, i) =>
        data[Math.floor(i / perPage) * perPage 
           + Math.floor((i % perPage) / numColumns) 
           + (i % numColumns) * numRows]
    );
}

let result = uncolumnize([0,2,4,6,8,1,3,5,7,9,10,12,14,16,18,11,13,15,17,19], 2, 5);
console.log(result);

This implementation utilizes the map Array method as the resulting array will have the same length as the original data. The callback specified for map only relies on the index rather than the value itself. This index assists in determining the page, row, and column information. By rearranging the row and column values, a new index is constructed which then retrieves the corresponding data.

Answer 3

Answer №2

10 elements in 2 columns per page will be grouped as

10n, 10n+2, 10n+4, 10n+6, 10n+8, 10n+1, 10n+3, 10n+5, 10n+7, 10n+9

There will be groups of 10 elements with the last group having 0-9 elements.

N = 5 //total rows
len = array.length //array contains numbers
groups_of_2n_len = len / (2 * N)
last_group_len = len % (2 * N)

//Process complete groups
for(group_i = 0; group_i < groups_of_2n_len; group_i = group_i + 1) {
    temp_array = array.slice(group_i * 2 * N, group_i * 2 * N + 2 * N)
    element = group_i * 2 * N

    for(temp_i = 0; temp_i < N; temp_i = temp_i + 1) {
        array[element] = temp_array[temp_i]
        array[element + 1] = temp_array[temp_i + N]
        element = element + 2
    }
}

//Handle last group
if(last_group_len == 0) return

temp_array = array.slice(groups_of_2n_len * 2 * N)

element = groups_of_2n_len * 2 * N

for(temp_i = 0; temp_i < Math.floor(last_group_len / 2); temp_i = temp_i + 1) {
    array[element] = temp_array[temp_i]
    array[element + 1] = temp_array[temp_i + Math.floor(last_group_len / 2) + last_group_len % 2]
    element = element + 2
}

Answer 4

10 elements in 2 columns per page will be grouped as

10n, 10n+2, 10n+4, 10n+6, 10n+8, 10n+1, 10n+3, 10n+5, 10n+7, 10n+9

There will be groups of 10 elements with the last group having 0-9 elements.

N = 5 //total rows
len = array.length //array contains numbers
groups_of_2n_len = len / (2 * N)
last_group_len = len % (2 * N)

//Process complete groups
for(group_i = 0; group_i < groups_of_2n_len; group_i = group_i + 1) {
    temp_array = array.slice(group_i * 2 * N, group_i * 2 * N + 2 * N)
    element = group_i * 2 * N

    for(temp_i = 0; temp_i < N; temp_i = temp_i + 1) {
        array[element] = temp_array[temp_i]
        array[element + 1] = temp_array[temp_i + N]
        element = element + 2
    }
}

//Handle last group
if(last_group_len == 0) return

temp_array = array.slice(groups_of_2n_len * 2 * N)

element = groups_of_2n_len * 2 * N

for(temp_i = 0; temp_i < Math.floor(last_group_len / 2); temp_i = temp_i + 1) {
    array[element] = temp_array[temp_i]
    array[element + 1] = temp_array[temp_i + Math.floor(last_group_len / 2) + last_group_len % 2]
    element = element + 2
}

Answer 5

Answer №3

https://www.w3schools.com/jsref/jsref_sort.asp

Highlighted example:

var nums = [6, 3, 8, 2, 5];
nums.sort(function(x, y) {
  return x - y;
});
console.log(nums);

// [2, 3, 5, 6, 8]

If you have numbers in two different arrays you can try this approach...

const arr1 = [10, 15, 20, 25, 30];
const arr2 = [35, 40, 45, 50, 55];
const merged = [...arr1, ...arr2];
console.log(merged);

Answer 6

https://www.w3schools.com/jsref/jsref_sort.asp

Highlighted example:

var nums = [6, 3, 8, 2, 5];
nums.sort(function(x, y) {
  return x - y;
});
console.log(nums);

// [2, 3, 5, 6, 8]

If you have numbers in two different arrays you can try this approach...

const arr1 = [10, 15, 20, 25, 30];
const arr2 = [35, 40, 45, 50, 55];
const merged = [...arr1, ...arr2];
console.log(merged);

Shuffle not JavaScript array!

Answer №1

Answer №2

Answer №3

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