Re: [january-dev] Question about IDataset

[Dinko Ivanov <dinko.ivanov@xxxxxxxxx>]

Hi Peter,

Let's consider an example:

    Dataset ds1 = DatasetFactory.createFromObject(Dataset.OBJECT, Arrays.asList(new PressureVsDepth(100, 2000), new PressureVsDepth(110, 2500)));   
    Dataset ds2 = DatasetFactory.createFromObject(Dataset.OBJECT, Arrays.asList(new PressureVsDepth(15, 2000), new PressureVsDepth(20, 2500)));

If I try to do ds1.iadd(ds2), it throws unsupported operation exception.
So if I understand correctly the idea here is to subclass the ObjectDataset and implement the various arithmetic operations, like iadd, imultiply, etc? And the objects in the dataset would be of some wrapper class (PressureVsDepth), holding two values, like pressure vs depth or time.

Thanks,
Dinko

On Wed, Jan 18, 2017 at 11:20 AM, <Peter.Chang@xxxxxxxxxxxxx> wrote:

Hi Dinko,

 

As you say, compound datasets do not support items that comprise elements of different type. So far we have concentrated on primitive arrays as these are memory-efficient in Java.

 

One possibility is to use ObjectDataset – we will need to add Java generic support (allow you to create subclasses of ObjectDataset<T>) for that to be useful. Otherwise, you use separate datasets for each of your quantities.

 

I’m not sure what you mean by “indexed”. Do you mean finding all positions in a nD volume of, say, depth is a given value? Then, you can write a position iterator loop which checks that depth dataset and adds the positions to a list.

 

Regards,

Peter

 

 

From: january-dev-bounces@eclipse.org [mailto:january-dev-bounces@eclipse.org] On Behalf Of Matthew Gerring
Sent: 17 January 2017 19:29
To: january developer discussions <january-dev@xxxxxxxxxxx>
Subject: Re: [january-dev] Question about IDataset

 

Hi Dinko,

 

This issue has come up before. I will ask Peter Chang what his recommended approach is. We will get back to you this evening or maybe tomorrow UK time.

 

Cheerio,

 

Matt

 

On 17 January 2017 at 19:22, Dinko Ivanov <dinko.ivanov@xxxxxxxxx> wrote:

Hi,

I'm working on an Eclipse RCP-based application that performs some statistical and numerical analysis on data. So far I'm using some in-house data structures for that, but I recently learned about the January project and I'd like to evaluate it.

My question is: how do I handle "indexed" datasets in January, where each value is a double measurement against some index - time, altitude, depth, etc? I tried using a CompoundDataset, but it requires nested datasets to be of the same time. Could you give some hints?

 

Thanks and best regards!

Dinko

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