Splitting a CSV into an object with javascript/jquery

Question

I have an ordered array which looks like this:-

[-0.0020057306590257895, 50, 0.09598853868194843, 50, 0.19398280802292264, 49.99999999999999, 0.2919770773638969, 50]

What I would like to do is the following:

• Take each 'odd' entry and make it the 'key index in an object, which can be achieved by rounding the value and multiplying by 10 e.g. (Math.round(-0.0020057306590257895 * 10) should be index 0 and Math.round(0.09598853868194843 * 10) should be index 1 etc)
• Take the 'even' values and make them the corresponding values in the object.

So...

The above CSV file should return the following object:-

{
  0: 50,
  1: 50,
  2: 49.99999999999999,
  3: 50
}

Does anyone one know how I can parse this CSV to produce the required array using either jQuery or plain javascript?

Answer 1

I'm going to assume you've done something to read the CSV file into a string since you said in the comments you tried using .split(",").

var csv = "-0.0020057306590257895, 50, 0.09598853868194843, 50, 0.19398280802292264, 49.99999999999999, 0.2919770773638969, 50";
var arr = csv.split(",");
var obj = {};
for (var i = 0; i < arr.length - 1; i += 2) {
    obj[Math.round(arr[i] * 10)] = arr[i + 1];
}

You should probably check that there are an even number of elements in the array first with something like if (arr.length % 2 == 0).

The things you should walk away with are:

1. {} curly braces are used to define an object, a pair of empty braces means the same thing as new Object() but using the braces is recommended.
2. [] square brackets can be used define an array or address both the elements of an array by their index (like arr[0]) and the properties of an object by their key (like obj['name']).

Answer 2

var arr = "-0.0020057306590257895, 50, 0.09598853868194843, 50, 0.19398280802292264, 49.99999999999999, 0.2919770773638969, 50".split(",");
var obj = {};

for (index = 0; index < arr.length - 1; index += 2) {
    var key = Math.round(parseFloat(arr[index]) * 10);
    var value = Math.round(parseFloat(arr[index + 1]) * 10);
    obj[key.toString()] = value.toString();
}

To get the value:

var keyVal = obj[key];

To delete a key value pair:

delete obj[key];

Hope this helps.

Answer 3

If your data structure is guaranteed to have a value for each integer (i.e. won't jump from say 3.9 straight to 5.9 in the even columns) you can save a bit of effort and use

var arr = "-0.0020057306590257895, 50, 0.09598853868194843, 50, 0.19398280802292264, 49.99999999999999, 0.2919770773638969, 50".split(",");
var result = [];

for (index = 0; index < arr.length - 1; index += 2) {
    result.push(parseFloat(arr[index + 1]));
}

NB - this also has numbers rather than a strings as its values due to using parseFloat