Re: Charting solutions
Re: Charting solutions
- Subject: Re: Charting solutions
- From: Drew McCormack <email@hidden>
- Date: Wed, 2 Apr 2003 08:37:43 +0200
For the type of scientific / numerical applications that I develop,
something like a pie chart is not going be to necessary. This type of
"warm and fuzzy" presentation is a distinctly different goal from the
fundamental graphs of technical data that we need immediately.
Maybe, maybe not. A pie chart may not be such a good example. But what
if you want something more complex, like error bars, or in my case a
plot that doesn't just have symbols like squares or circles, but more
complex symbols that depend on 4 different y values for each x
(Open-High-Low-Close or candlestick charting in finance). Or for a more
scientific example, a polar chart, or a triangular coordinate chart.
I fully agree that XYPlot will meet most needs in terms of quickly
throwing together a scatter plot or histogram, but I think it will not
be that easy to extend if it doesn't quite meet your requirements.
Narrative was designed for this type of evolution.
So, I think that the search simple 2D chart / graphics toolkit is
basically resolved for now. For basic 2D plotting in Cocoa, I am
going to adopt XYPlot and build on it. I will commit to releasing
some more advanced GUI / palette versions based on it.
I agree. I think Narrative is a broader-based project, that could offer
plotting solutions for people in wider fields. Maybe it is also not as
familiar to scientists, being so strongly OO. XYPlot works more like
other 2D plotting libraries like gnuplot.
For those interested in Cocoa Numerics, within the XYPlot project
there is a very well developed class that I think represents something
missing in the current Cocoa Foundation (again, re-authored by Sean
Hill) . It is called NSValueArray, and it let us handle and
manipulate numerical arrays as NSArrays (instead of C pointers).
Like, the Foundation class is also defined in a mutable form:
NSMutableValueArray. Below I have posted NSValueArray.h for the
curious.
I like NSValueArray, but I don't really think it belongs in Foundation.
I think most people can get by with NSData and friends. Those that
really need it can just install NSValueArray themselves.
NSValueArray is basically just NSData with typed data. It's very
useful, but what I would love to see is a multidimensional array class,
like what is found in python. That would be really powerful for
scientific programming.
Cheers,
Drew
======================================
Dr. Drew McCormack (Kmr. R153)
Afd. Theoretische Chemie
Faculteit Exacte Wetenschappen
Vrije Universiteit Amsterdam
De Boelelaan 1083
1081 HV Amsterdam
The Netherlands
Email email@hidden
Telephone +31 20 44 47623
Mobile +31 6 483 21307
Fax +31 20 44 47629
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