Plotting Using PLPlot

Fawzi Mohamed fmohamed at
Sun May 10 22:51:28 PDT 2009

On 2009-05-11 02:05:51 +0200, Robert Fraser <fraserofthenight at> said:

> dsimcha wrote:
>> == Quote from Fawzi Mohamed (fmohamed at's article
>>> On 2009-05-10 21:23:48 +0200, dsimcha <dsimcha at> said:
>>>> It seems like there's substantial interest in this.  Please give me some use
>>>> cases, i.e. what would you personally use this for, and what do you
>>>> foresee others
>>>> using it for, so I can start thinking about what the API should be.  I
>>>> need a wide
>>>> variety of use cases because, if I design the API based only on my personal use
>>>> cases, it will end up being geared entirely toward histograms, scatter
>>>> plots, and
>>>> line graphs because that's what I use regularly.
>>> yep me too, well 3d surface plots would also be nice to have, but I can
>>> live without.
>>>> Besides use cases, here are some specific questions:
>>>> 1.  Is there any need for an OO-based API, or should I just use free functions?
>>> I would use an OO API where one window/image/output graph is
>>> represented by an object, and then you have functions to
>>>> 2.  Does anyone have any use cases where plotting is performance critical, or
>>>> should I just keep things simple/stupid in terms of the performance/simplicity
>>>> tradeoff?
>>> keep it simple I would just send dense arrays to it (which are close to
>>> the C api), and then have utility functions that convert ranges,... to
>>> dense arrays, but maybe I am biased because I have a good library to
>>> handle dense arrays.
>>> I would say that a reasonable goal is that the library could cope
>>> directly to plot of 1'000s of points at least for the simple 1D plot
>>> types.
>> Ok, this is way less than I had in mind.  When I said high performance, I was
>> thinking like, either plotting stuff under realtime constraints like if you're
>> some Wall Street bigwig plotting zillions of charts to figure out what 
>> stocks to
>> buy or, when doing summary stuff like histograms, handling billions of 
>> points read
>> as a range from a file, i.e. more data than you have address space.  I 
>> personally
>> would not consider anything that couldn't gracefully handle at least a 
>> few million
>> data points for histograms and a few 10s of thousands for scatter plots 
>> to be good
>> enough.
> Having plots that update in realtime would be kind of awesome for 
> monitoring, but the ones I was thinking of wouldn't be more than a few 
> thousand data points in each sliding window, if that.

my answer was along the keep it simple lines, you cannot really expect 
to represent more than some 1000s of points, if you have more you 
should do some transformation to represent them.

Histogram for example reduce them, some cluster or spread analysis and 
represent fewer discrete objects,...

All those things can be built later, the only thing needed is a basic 
lib that supports few 1000s of simple objects well, and less of complex 
even realtime update an animations can be done if the library is fast 
for its basic use.

Keep it simple, the fancy stuff can be built on the top of it later.

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