RE: [Numpy-discussion] Status of Numeric (and plotting in particular)

[Kuzminski, S. R <SKu...@fa...>]

I'm working on a commercial product that produces publication quality
plots from data contained in Numeric arrays.  I also concluded that
Chaco was a bit more involved than I needed.  My question is what
requirements are not met by the other available plotting packages such
as..

http://matplotlib.sourceforge.net/=20

These don't have every bell and whistle ( esp. when it comes to the
interactive 'properties' dialog ) but as you point out there is a dark
side to those features.=20

There are a number of quite capable plotting packages for Python,
diversity is good up to a point, but this space ( Plotting packages )
seems ripe for a shakeout. =20

Stefan


-----Original Message-----
From: num...@li...
[mailto:num...@li...] On Behalf Of Perry
Greenfield
Sent: Tuesday, January 20, 2004 7:02 PM
To: Chris Barker
Cc: num...@li...
Subject: Re: [Numpy-discussion] Status of Numeric (and plotting in
particular)


On Tuesday, January 20, 2004, at 06:08 PM, Chris Barker wrote:

>> Perry Greenfield writes:
>
>>  > It has been our intention to port scipy to use numarray soon.
This
>>  > work has been delayed somewhat since our current focus is on
>>  > plotting.
>
> That is good news. What plotting package are you working on? Last I=20
> heard Chaco had turned into Enthought's (and STSci) in-house  Windows=20
> only package. (Not because they want it that way, but because they=20
> don't have funding to make it work on other platforms, and support the

> broader community).
>
> I don't see anything new on the SciPy page after August '03.
>
> Frankly, weak plotting is a bigger deal to me than array performance.
>
Yes, I agree completely (and why we are giving plotting higher priority=20
than scipy
integration).

I really was hoping to raise this issue later, but I might as well=20
address it since
the Numeric/numarray issue has raised it indirectly.

Chaco had been the focus of our plotting efforts for more than a year.=20
The effort
started with our funding Enthought to start the effort. We had a number=20
of requirements
for a plotting package that weren't met by any existing package, and it=20
didn't appear
that any would be easily modified to our needs. The requirements we had=20
(off the
top of my head) included:

1) easy portability to graphics devices *and* different windowing=20
systems.
2) it had to run on all major platforms including Solaris, Linux, Macs,=20
and Windows.
3) the graphics had to be embedable within gui widgets.
4) it had to allow cursor interactions, at least to the point of being=20
able to read
    cursor positions from python.
5) it had to be open source and preferably not gpl (though the latter=20
was probably not
    a show stopper for us)
6) It also had to be customizable to the point of being able to produce=20
very high
    quality hardcopy plots suitable for publication.
7) object oriented plotting framework capable of sensible composition.
8) command line interface akin to that available in matlab or IDL to=20
make producing
    quick interactive plots very, very easy.

Developing something that satisfies these is not at all trivial.

In the process Enthought has expended much energy developing chaco,=20
kiva and traits
(and lately they are working on yet more extensions); easily much more=20
of the effort
has come from sources other than STScI. Kiva is the back end that=20
presents a uniform
api for different graphics devices. Traits handles many of the user=20
interface issues
for plot parameters, and handling the relationships of these parameters=20
between
plot components. Chaco is the higher level plotting software that=20
provides the traditional
plotting capabilities for 2-d data. Much has been invested in chaco.

It is with some regret that we (STScI) have concluded that chaco is not=20
suitable for
our needs and that we need to take a different approach (or at least=20
give it a try).
I'll take some space to explain why.

The short answer is that in the end we think it was too ambitious. We=20
still aim
to achieve the goals I listed above. The problem we think is that chaco=20
was also
tasked to try to achieve extra goals with regard interactive=20
capabilities that
were in the end, not really important to STScI and it's community, but=20
were
important to Enthought (and presumably its clients, and the scipy=20
community).

More specifically, a lot of thought and work went into making many=20
aspects of the
plots could be interactively modified. That is, by clicking on various=20
aspects
of plots, one could bring up editors for the attributes of that plot=20
element,
such as color, line style, font, size, etc. Many other interactive=20
aspects
have been enhanced as well. Much recent work by Enthought is going into=20
extending
the capabilities even further by adding gui kinds of features (e.g.,=20
widgets of
all sorts).

Unfortunately these capabilities have come at a price, namely=20
complexity. We
have found it difficult to track the ongoing changes to chaco to become=20
proficient
enough to contribute significantly by adding capabilities we have=20
needed.
Perhaps that argues that we aren't competent to do so. To a certain=20
degree,
that is probably is true. There is no doubt that Enthought has some=20
very talented
software engineers working on chaco and related products. On the other=20
hand,
our goal is to have this software be accessible by scientists in=20
general, and
particularly astronomers. Chaco is complex enough that we think that is=20
a
serious problem. Customizing it's behavior requires a very large=20
investment of
time understanding how it works, far beyond what most astronomers are=20
willing
to tackle (at least that's my impression).

Much of this complexity (and many of its ongoing changes) is to support=20
the
interactive capabilities, and to make it responsive enough that plots=20
can
update themselves quickly enough not to lead to annoying lags. But=20
frankly,
we just want something to render plots on the screen and on hardcopy.=20
Outside
of being able to obtain cursor coordinates, we find many of the=20
interactive
capabilities as secondary in importance. When most astronomers want to=20
tune
a plot (either for publication quality, or for batch processing), they=20
usually
want to be able to reproduce the adjustments for new data, for which=20
the interactive
attribute editing capability is of little use. Generally they would=20
like to
script the the more customized plots so that they can be easily=20
modified and
reused.

So it seems that it is too difficult to accomplish all these aims=20
within one
package. We would like to develop a different plotting package (using=20
many of
ideas from chaco, and some code) based on kiva and the traits package.
We have started on this over the past month, and hope to have some=20
simple
functionality available within a month (though when we make it public=20
may
take a bit longer). It will be open source and we hope significantly=20
simpler
than chaco. It will not focus on speed (well, we want fairly fast=20
display times
for plots of a reasonable number of points, but we don't need video=20
refresh
rates). If your interest in plotting matches ours, then this may be for=20
you.
We will welcome contributions and comments once we get it off the=20
ground.
(We are calling it pyxis by the way).

Enthought is continuing to work on chaco and at some point that will be=20
mature,
and will be capable of some sophisticated things. That may be more=20
appropriate
for some than what we are working on.

Perry Greenfield



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