gnuplot-py-users Mailing List for Gnuplot.py

Thomas Pfaff wrote:

>>Why are you so allergic to temporary files? In most cases they
>>won't be significantly slower, as the bulk of the time is for
>>Python to format the data as ASCII data, which has to be done
>>anyway.
>>
>>Write yourself a little helper function like utils.write_array()
>>but which is smart about date-formatted data. File PlotItems can
>>take arbitrary strings as their "using" argument. What else do you
>>need?
>>
>>    
>>
>Well, basically I didn't like the thought of "having to". In all cases
>regular PlotItems work fine, except for time-data where I would "have
>to" use File PlotItems just because only they would accept the using
>keyword, which seemed to me like some kind of a workaround.
>  
>

What's missing isn't the "using" functionality; it's the ability to 
include date information in data to be sent to gnuplot, and the ability 
to format the date information in a way that gnuplot can read.  
Gnuplot.py uses Numeric arrays to hold the data to be plotted (at least 
when using the Data PlotItem), and I don't know of a good way to store 
date information within a Numeric array.  Therefore the input to Data 
would have to be in a different form to even get started supporting dates.

>Maybe if I understood the concept behind the interaction with gnuplot
>.... If you say that Python has to format the data as ASCII data
>anyway, is it maybe that Python just creates ASCII lines in gnuplot
>format from the data which are then fed to gnuplot via a pipe?
>

That is correct, though depending on your settings the data might be 
transferred inline via the gnuplot command-input pipe, via a named pipe, 
or via a temporary file.

> If I
>can know beforehand how the final line would look like (the data from
>the array marked as x-data would be the first in line, followed by the
>y-data and so on), wouldn't it suffice to have all PlotItems accept
>the 'using' keyword, and then I would just say "using 1:3" if my
>date-strings contained a space?
>  
>

I think the real problem is that dates cannot be expressed as 
space-separated columns of numbers (or can they...?)  Gnuplot.py doesn't 
have a way to output arbitrary strings, at least not via the Data PlotItem.

Let us know what you work out,
Michael

Lozza Hyde wrote:

> I think I may have posted once before but I can't remember and I still 
> haven't sorted out my problems.
> I've been trying to install gnuplot for py for nearly 6 months and 
> different install are giving me different problems.  I'm running F3 
> and the latest version of gnuplot tells me that it cannot find python...
> If anyone else has had this problem could you please tell me how to 
> fix it???


It's a little hard to help without more information.  What operating 
system?  What exactly did you do and what error message did you get?

Normally, you start python via some other mechanism then import Gnuplot 
via python's "import" command.  So problems finding python usually have 
to be resolved before you can even start Gnuplot.

Michael

I think I may have posted once before but I can't remember and I still 
haven't sorted out my problems.
I've been trying to install gnuplot for py for nearly 6 months and different 
install are giving me different problems.  I'm running F3 and the latest 
version of gnuplot tells me that it cannot find python...
If anyone else has had this problem could you please tell me how to fix 
it???

Cheers,
Lozza