I've already tried to find a solution on stack, but I didn't found a possible reply, so I decided to open a topic to ask:
Let's say we have 2 arrays: one containing "keys" and another one containing "values"
Example:
keys = [CO2, Blood, General, AnotherKey, ... ]
values = [[2,5,4,6],[4,5,6],[1,3,34.5,43.4],[... [
I have to create a Json with a specific structure like:
[{
name: 'CO2',
data: [2,5,4,6]
}, {
name: 'Blood',
data: [4,5,6]
}, {
name: 'General',
data: [1,3,34.5,43.4]
}, {
...
},
}]
I've tried to make some test bymyself, like concatenate strings and then encode it as json, but I don't think is the correct path to follow and a good implementation of it ... I've also take a look on JSON.PARSE, JSON.stringify, but I never arrived at good solution so... I am asking if someone know the correct way to implements it!
EDIT:
In reality, i didn't find a solution since "name" and "data" are no strings but object
Here's one way to get your desired output:
keys = ["CO2", "Blood", "General", "AnotherKey"]
values = [[2,5,4,6],[4,5,6],[1,3,34.5,43.4],[0] ]
const output = keys.map((x, i) => {
return {"name": x, "data": values[i]}
})
console.log(output)
However, since you're literally constructing key/value pairs, you should consider whether an object might be a better data format to output:
keys = ["CO2", "Blood", "General", "AnotherKey"]
values = [[2,5,4,6],[4,5,6],[1,3,34.5,43.4],[0] ]
const output = {}
for (let i=0; i<keys.length; i++) {
output[keys[i]] = values[i]
}
console.log(output)
With this data structure you can easily get the data for any keyword (e.g. output.CO2). With your array structure you would need to iterate over the array every time you wanted to find something in it.
(Note: The reason you weren't getting anywhere useful by searching for JSON methods is that nothing in your question has anything to do with JSON; you're just trying to transform some data from one format to another. JSON is a string representation of a data object.)
Related
I am working on a project that has JSON format output. I need a clarity on the JSON array structure. So There are fields that are multiple entry like an array. If an element is an array but has only one value, does it still include an array node '[' in the structure?
Example:
This is a sample JSON element which is an array and has multiple values.
"Talents": [
{
"Items": "test"
},
{
"Items": "test"
}
]
If this element does not have multiple values, will it appear as below?
"Talents":
{
"Items": "test"
}
The '[' does not appear for an array type element with single value. Can someone Pls clarify this?
Single-item arrays will still include the array brackets in JSON format, as they are still arrays. In other words, there is no such native mechanism which converts single-item arrays to a non-array representation. So with your single-item example, it would be represented like this:
"Talents": [
{
"Items": "test"
}
]
You can easily test this out with some simple code:
let jsonSingleItem = { "Talents": [ {"Items": "item1"} ] };
let arraySingleItem = [ {"Items": "item1"} ];
console.log(JSON.stringify(jsonSingleItem));
console.log(jsonSingleItem);
console.log(arraySingleItem);
Which yields the following output:
{"Talents":[{"Items":"item1"}]}
{ Talents: [ { Items: 'item1' } ] }
[ { Items: 'item1' } ]
So in all cases (a stringified JSON object, native JSON, and a javascript array) the single item is still in an array.
Note: It is not uncommon that a consumer of an API will send data (i.e. JSON) in ways which are outside the agreed-upon contract/schema that API defines, and this (sending an object instead of a single-object array when there is just one item) is one example I have seen before. It would be up to the owner/developer of the API as to whether they build in flexibility to handle input which deviates from the API schema.
Square brackets ("[]") denotes JSONArray which in your case can access like
Talents[0]
will return
{
"Items": "test"
}
In second case, curve brackets denotes an JSON object. If you want to access value of items. Than you can by
Talents.Items
OR
Talents["Items"]
will return
"Test"
for complete reference,
JSON Syntax
I'd like to visualize data pulled in from the census data API, specifically from the ACS survey.
The data is returned in a non-standard version of JSON, as a two-dimensional array. It basically looks like this:
[
[
“POPULATION”,
“DATE”,
“ANOTHERTHING”
],
[
“ALABAMA”,
“2000”,
“MORESTUFF”
],
[
“ALASKA”,
“2000”,
“OTHERSTUFF”
],
…
]
I'm unfamiliar with working with this kind of JSON data, which almost looks more like a CSV, where the keys are written in the first line, and the values in every line after the first.
Is anyone familiar with how to parse and work with this data in D3, without having to go convert it first (i.e. https://gist.github.com/sarfarazansari/7e8ae05168b80b36016eb1c561a82f73)? (I'd like to draw from the data API directly).
Any help or guidance would be much appreciated.
First of all: do not use smart quotes (“) in a JSON (or in your code, whatever it is). I reckon that your real JSON is correct, this just happened because you used a text editor, like MS Word, to write this question. Also, there is no such a thing like non-standard JSON, because there is no standard JSON to begin with. You just have a JSON which is an array of arrays, nothing special here.
That being said, you can use that exact data structure to create your charts... However, specially if you're a beginner, it's a good idea to stick with the most common (here we can say standard) way to organise the data in D3 codes, which is an array of objects.
We can easily convert that array of arrays in an array of objects, which will be more comfortable to you.
First, supposing that your array is named data, let's extract the headers:
var keys = data.shift();
That not only creates a headers array, but it will remove the first inner array from the data array.
Now, we iterate over each inner array, creating an object with all the key/value pairs we need:
var newData = data.map(function(d) {
var obj = {};
d.forEach(function(e, i) {
obj[keys[i]] = e;
});
return obj;
});
There are shorter ways to do this, the one above is quite verbose but it is more didactic.
Here is a demo using the data you shared:
var data = [
[
"POPULATION",
"DATE",
"ANOTHERTHING"
],
[
"ALABAMA",
"2000",
"MORESTUFF"
],
[
"ALASKA",
"2000",
"OTHERSTUFF"
]
];
var keys = data.shift();
var newData = data.map(function(d) {
var obj = {};
d.forEach(function(e, i) {
obj[keys[i]] = e;
});
return obj;
});
console.log(newData)
<script src="https://d3js.org/d3.v5.min.js"></script>
Is there exist any kind of c# dictionary in JavaScript. I've got an app in angularjs that requests data from an MVC Web Api and once it gets, it makes some changes to it. So the data is an array of objects, which is stored in the MVC Web Api as a Dictionary of objects, but I convert it to list before passing it throug network.
If I convert the Dictionary directly to JSon I get something like:
array = [ {Id:"1", {Id:"1", Name:"Kevin Shields"}},
{Id:"2", {Id:"2", Name:"Natasha Romanoff"}}
];
Well the objects are a little more complex, but you've got now an idea. The problem is that this format is even harder to operate with (I've got alphabetical keys or ids). So is there any equivalent to a dictionary? It's quite simple to do thing like:
Object o = dictionary["1"];
So that's it, thank in advance.
You have two options really, although both essentially do the same thing, it may be worth reading a bit more here, which talks about associative arrays (dictionaries), if you wish to tailor the solution:
var dictionary = new Array();
dictionary['key'] = 'value'
Alternatively:
var dict = [];
dict.push({
key: 'key',
value: 'value'
});
Update
Since ES2015 you can use Map():
const dict = new Map();
dict.set('{propertyName}', {propertyValue});
I know this question is a bit older, but in ES2015 there is a new data structure called map that is much more similar to a dictionary that you would use in C#. So now you don't have to fake one as an object, or as an array.
The MDN covers it pretty well. ES2015 Map
Yes, it's called an object. Object have keys and values just like C# dictonaries. Keys are always strings.
In your case the object would look like this:
{
"1": {
"Id": 1,
"Name":" Kevin Shields"
},
"2": {
"Id": 2,
"Name": "Natasha Romanoff"
}
}
The default ASP.net serializer produces ugly JSON. A better alternative would be Json.NET.
My Example:
var dict = new Array();
// add a key named id with value 111
dict.id = 111;
//change value of id
dict.id = "blablabla";
//another way
// add a key named name with value "myName"
dict["name"] = "myName";
//and delete
delete dict.id;
delete dict["name"]
//another way
dict = {
id: 111,
"name": "myName"
};
//And also another way create associate array
var myMap = { key: [ value1, value2 ] };
I'm a perl programmer learning javascript. In perl, I would frequently use hashes to create 'data structures' from data returned from a database query. For example, I would build hashes like this:
*loop through list of data*
push(#{$hash{$key1}{$key2}}, [$value1, $value2, $value3, $value4]);
*endloop*
this would add a reference to the list of four values to a list in the hash (with multiple keys).
I'm having a hard time finding information on how I would implement a similar structure in javascript. My goal is to read in a JSON file that has a list of objects (which has no particular order) and turn it into a hash so it can be sorted by the keys and then display it in an HTML table.
Perhaps this is the wrong way to think about this problem and javascript will have a different approach. I'd like to know if what I'm trying to do is possible, the code to create the hash, and the code to access the hash.
Thanks,
Rob
This is my straight translation, tested at the Google Chrome console prompt >
> hash = {}
Object {}
> hash["key1"] = {}
Object {}
> hash["key1"]["key2"] = []
[]
> hash["key1"]["key2"].push([ 'value1', 'value2', 'value3', 'value4'])
1
> hash
Object {key1: Object}
> JSON.stringify(hash, null, 2)
"{
"key1": {
"key2": [
[
"value1",
"value2",
"value3",
"value4"
]
]
}
}"
Hash in Perl is just set of key/value pairs. Javascript has similar data structure - Objects. You could do what you want
> a = {}
{}
> a.res = []
[]
> a.res.push([1,2,3])
1
> a.res.push([3,"sd",1])
2
> a
{ res:
[ [ 1, 2, 3 ],
[ 3, 'sd', 1 ] ] }
Javascript does not have an ordered hash and a lookup with multiple keys. You can use the properties of an object to create a lookup by a single unique key and you can then build on that notion as needed. See this answer for an idea how to implement a simple form of hash or set in javascript.
The basic idea is that you create an object and then add key/value pairs to it:
var myLookup = {};
myLookup[key1] = value1;
myLookup[key2] = value2;
Then, you can look up a value by the key:
console.log(myLookup[key1]); // shows value1
If you want more specific help, you will have to be more specific in your question. Show us what the JSON you start with and describe exactly how you want to be able to access it so we can figure out what type of JS data structure makes the most sense to put it in. Remember, once the JSON is parsed, it is already in a javascript data structure at that point so the it becomes a question of what kind of access you need to make to the data to understand whether the data should be restructured with certain key lookups?
It is generally best to concentrate on problem/solution and NOT on trying to do something the same way another language does it.
I am kind of new to the world of interface, and i found JSON is amazing, so simple and easy to use.
But using JS to handle it is pain !, there is no simple and direct way to push a value, check if it exists, search, .... nothing !
and i cannot simply add a one single value to the json array, i have this :
loadedRecords = {}
i want to do this :
loadedRecords.push('654654')
loadedRecords.push('11')
loadedRecords.push('3333')
Why this is so hard ???!!!
Because that's an object, not an array.
You want this:
var = loadedRecords = []
loadedRecords.push('1234');
Now to your points about JSON in JS:
there is no simple and direct way to push a value
JSON is a data exchange format, if you are changing the data, then you will be dealing with native JS objects and arrays. And native JS objects have all kinds of ways to push values and manipulate themeselves.
check if it exists
This is easy. if (data.someKey) { doStuff() } will check for existence of a key.
search
Again JSON decodes to arrays and objects, so you can walk the tree and find things like you could with any data structure.
nothing
Everything. JSON just translates into native data structures for whatever language you are using. At the end of the day you have objects (or hashes/disctionaries), and arrays which hold numbers strings and booleans. This simplicity is why JSON is awesome. The "features" you seek are not part of JSON. They are part of the language you are using to parse JSON.
Well .push is an array function.
You can add an array to ur object if you want:
loadedRecords = { recs: [] };
loadedRecords.recs.push('654654');
loadedRecords.recs.push('11');
loadedRecords.recs.push('3333');
Which will result in:
loadedRecords = { recs: ['654654', '11', '3333'] };
{} is not an array is an object literal, use loadedRecords = []; instead.
If you want to push to an array, you need to create an array, not an object. Try:
loadedRecords = [] //note... square brackets
loadedRecords.push('654654')
loadedRecords.push('11')
loadedRecords.push('3333')
You can only push things on to an array, not a JSON object. Arrays are enclosed in square brackets:
var test = ['i','am','an','array'];
What you want to do is add new items to the object using setters:
var test = { };
test.sample = 'asdf';
test.value = 1245;
Now if you use a tool like FireBug to inspect this object, you can see it looks like:
test {
sample = 'asdf,
value = 1245
}
Simple way to push variable in JS for JSON format
var city="Mangalore";
var username="somename"
var dataVar = {"user": 0,
"location": {
"state": "Karnataka",
"country": "India",
},
}
if (city) {
dataVar['location']['city'] = city;
}
if (username) {
dataVar['username'] = username;
}
Whats wrong with:
var loadedRecords = [ '654654', '11', '333' ];