converting a multidimensional JavaScript array into an associative array

Question

converting a multidimensional JavaScript array into an associative array

I have extracted an array from a local database and it consists of various entries.

var data = [
  ['09-08-2017', '62154', 'Approved'],
  ['09-08-2017', '62155', 'Approved'],
  ['08-25-2017', '61922', 'Approved'],
  ['08-25-2017', '61923', 'Approved'],
  ['08-18-2017', '61949', 'Approved'],
  // ...
];

There are approximately 250 different entries in this array. Each entry contains information about the date, job number, and job state.

The first element of each sub-array represents the date of the week of the job, with each week corresponding to the Friday of that week.

The second element is the job number, which is unique for each job but there can be multiple job numbers per week.

The third element represents the job state, which needs to stay associated with the corresponding job number.

My goal is to convert this array into a shifted format where all job numbers and states are grouped together based on the date:

For example:

data['09-08-2017'] = ['62154', 'Approved'], ['62155', 'Approved'];

or possibly as an object:

data['09-08-2017'] = { jobNumber: '62154', jobState: 'Approved' };

I'm unsure how to initialize this new structure or the best way to perform the conversion. Any help or advice would be greatly appreciated. Thank you!

EDIT: I discovered why the initial array was formatted strangely. When transferring an array from PHP to JavaScript, I initially used:

var data = <?php json_encode(print_r($data)); ?> ;

After further research, I changed it to:

var data = <?php echo json_encode(array_values($data)); ?>;

This not only fixed the issue but also provided a more manageable format for my array.

javascript arrays

Answer 1

Answer №1

To modify the arrays, you can loop through the outer array and create new arrays based on the date values. Then add a new object to the arrays.

var data = [['09-08-2017', '62154', 'Approved'], ['09-08-2017', '62155', 'Approved'], ['08-25-2017', '61922', 'Approved'], ['08-25-2017', '61923', 'Approved'], ['08-18-2017', '61949', 'Approved']],
    object = data.reduce(function (r, a) {
        (r[a[0]] = r[a[0]] || []).push({ jobNumber: a[1], jobState: a[2] });
        return r;
    }, Object.create(null));

console.log(object);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

To modify the arrays, you can loop through the outer array and create new arrays based on the date values. Then add a new object to the arrays.

var data = [['09-08-2017', '62154', 'Approved'], ['09-08-2017', '62155', 'Approved'], ['08-25-2017', '61922', 'Approved'], ['08-25-2017', '61923', 'Approved'], ['08-18-2017', '61949', 'Approved']],
    object = data.reduce(function (r, a) {
        (r[a[0]] = r[a[0]] || []).push({ jobNumber: a[1], jobState: a[2] });
        return r;
    }, Object.create(null));

console.log(object);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 3

Answer №2

In JavaScript, there are no "associative arrays," only objects and the Map data structure introduced in ES2015.

If you want to transform an array of arrays into an object where each date corresponds to a set of job numbers and states, you can achieve this by creating empty objects using curly braces like so:

var obj = {};

You can then populate these objects with the appropriate information as follows:

obj["09-08-2017"] = {};

To add job numbers and states for each date, you can use object initializers:

obj[entry[0]] = {
    jobNumber: entry[1],
    jobState:  entry[2]
};

However, keep in mind that having multiple entries for the same date may not be feasible with this structure. A possible alternative could look something like this:

{
    "08-09-2017": {
        12345: "Approved",
        67894: "Approved"
    }
}

Here's an example illustrating how you can organize your data:

var data = [
    ["09-08-2017", 62154, "Approved"],
    ["09-08-2017", 12345, "Approved"],
    ["08-08-2017", 62155, "Approved"]
];
var obj = {};
data.forEach(function(entry) {
    var date = entry[0];
    if (!obj[date]) {
        obj[date] = {};
    }
    obj[date][entry[1]] = entry[2];
});
console.log(obj);

Answer 4

In JavaScript, there are no "associative arrays," only objects and the Map data structure introduced in ES2015.

If you want to transform an array of arrays into an object where each date corresponds to a set of job numbers and states, you can achieve this by creating empty objects using curly braces like so:

var obj = {};

You can then populate these objects with the appropriate information as follows:

obj["09-08-2017"] = {};

To add job numbers and states for each date, you can use object initializers:

obj[entry[0]] = {
    jobNumber: entry[1],
    jobState:  entry[2]
};

However, keep in mind that having multiple entries for the same date may not be feasible with this structure. A possible alternative could look something like this:

{
    "08-09-2017": {
        12345: "Approved",
        67894: "Approved"
    }
}

Here's an example illustrating how you can organize your data:

var data = [
    ["09-08-2017", 62154, "Approved"],
    ["09-08-2017", 12345, "Approved"],
    ["08-08-2017", 62155, "Approved"]
];
var obj = {};
data.forEach(function(entry) {
    var date = entry[0];
    if (!obj[date]) {
        obj[date] = {};
    }
    obj[date][entry[1]] = entry[2];
});
console.log(obj);

converting a multidimensional JavaScript array into an associative array

Answer №1

Answer №2

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