gnuplot-py-users Mailing List for Gnuplot.py

Michael Haggerty schrieb:

> 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
>
Well a simple form would be to use numbers according to the %s format,
which would be seconds since the UNIX-epoch (1970-01-01, 00:00 UTC).
I would prefer Julian dates, as they cover a larger period of time (1
Jan 4716 B.C.E. to 31 Dec 5000000 AD), but one would have to ask the
gnuplot-developers to offer that functionality, I suppose; that's
nothing gnuplot.py can do.

Another possibility, if you just need numbers separated by spaces, might
be  "2005 04 27 00 00 00" which would be "%y %m %d %H %M %S" for the
time format string. Actually I just read in the gnuplot help, that the
above format string would also recognize the "number" 20050427000000 as
spaces in format strings stand for zero or more spaces. However it would
need 64bit integers to represent such numbers.

Yet still I suppose gnuplot will still try to read a string using some
kind of strptime function?

Cheers,


Thomas

-- 
_______________________________________________________

Dipl.-Ing Thomas Pfaff, M.Eng.

Dr.-Ing. Karl Ludwig
Beratender Ingenieur
Wasserwirtschaft - Wasserbau
Herrenstr. 14
76133 Karlsruhe

Tel: 0721 / 91251-46
Fax: 0721 / 91251-19

tho...@lu...

The exact error it is giving me is "Cannot find python" after the 
dependencies check.  Like I said in my first email, I'm running Fedora Core 
3.  I've had no problems with any other modules just gnuplot.  This is what 
happens when I run the "automakic" install, when I rpm it, the thing tells 
me that it cannot find blas or cblas, both of which are most definitely 
installed on my computer.

Cheers,
Lozza

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

Edurne Dehesa wrote:

>is there any way to introduce a line with a concrete character while creating 
>a file, so that I can plot every piece of file between those characters as an 
>individual plot, once above the others?? I mean... I want to save in a file 
>several points, of several people. Then I want to compare all those people in 
>a graph, so I want to plot each person's respective points in a different 
>color and so on.  
>Thank you very much if you can help me.
>  
>

Is there a special reason that you want to write them to a single file 
before plotting them?  Because it would be much easier to plot lots of 
little PlotItems:

items = []

for person in person_list:
    items.append(Data(person.data, title=person.name)]

# Plot all of the datasets at once:
g.plot(*items)


I hope this helps,
Michael

Thomas Pfaff wrote:

>I'm not yet a subscriber to this list, so please send at least a CC of
>your answers to me personally.
>
>I used gnuplot.py quite extensively a couple of years ago and I really
>loved it, except for the problem that the gnuplot process needed the
>'using' keyword when plotting time-series data. As the PlotItems of
>that time didn't allow setting the using-keyword I was forced to work
>with temporary files which takes away much of the speed and comfort of
>having python controlling gnuplot.
>
>[...]
>
>So my question is, if there is any way to trick the gnuplot process
>into using python-arrays that contain time-series information without
>resorting to temporary files? I would be back to gnuplot and python in
>no time :-)
>  
>

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?

Cheers,
Michael

sven wrote:

> i'm using gnuplot to plot waveforms and sonograms under windows.
> as i'm having up to 10 plotwindows on the screen it would be nice
> to have the possibility to set the positions and sizes of the windows
> from py. is it possible and if so, how?


If you can do it from the gnuplot program itself, then you can do it 
from Gnuplot.py.  The best place to start would be to start up the 
command-line version of gnuplot then type "help term windows" and see if 
it offers any appropriate options.  If so, you can set them manually.

Michael

Casper Sharma wrote:

>This is a pretty simple question and I'd really
>appreciate any help.  I have a simple file of data
>points that I am plotting using a python script piped
>to gnuplot.  Does anyone know how i can get gnuplot to
>add the best fit line for these points.
>  
>

This was discussed a while ago on this mailing list.  See

    
http://sourceforge.net/mailarchive/forum.php?thread_id=2853843&forum_id=11272
    
http://sourceforge.net/mailarchive/forum.php?thread_id=2871643&forum_id=11272

Michael

Hi,

This is a pretty simple question and I'd really
appreciate any help.  I have a simple file of data
points that I am plotting using a python script piped
to gnuplot.  Does anyone know how i can get gnuplot to
add the best fit line for these points.

Thanks,
Divye Sharma

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On Mon, 2005-04-18 at 10:39 +0200, Edurne Dehesa wrote:
>     Gnuplot.plot 'fichero0' with linespoints, 'fichero1' with linespoints
>                           ^
> SyntaxError: invalid syntax

Have a look at the examples, the plot object is not just a
prefix to the usual command line, but you can use it somewhat
that way.  For example

   pobj = Gnuplot.Gnuplot()

   pobj( 'plot "file" with points, "fileb" with lines' )

or, from one of my scripts

    pobj = Gnuplot.Gnuplot()
    pobj.xlabel( xlab )
    pobj.ylabel( ylab )
    pobj( 'set zlabel "' + zlab + '"' )
    pobj( 'set view 70,340,1.10' )
    pobj( 'set grid xtics ytics' )
    pobj( 'set contour' )
    pobj( 'set cntrparam levels 10' )
    pobj( 'set terminal png small transparent' )
    pobj( 'set output "' + fileName + '"' )

    dobj1 = Gnuplot.GridData( d1, x, y,
                              Gnuplot.PlotItems._unset, 
                              title=d1Title, 
                              with="lines" ),

    pobj.splot( dobj1 )

    pobj.reset()

> I would be also pleased if you could help me with another question: can I 
> change names to every point in the axis??

Maybe you could construct a list of the points then use the more
complex form of "set xtics".   See 'help set xtics' in Gnuplot.
If your dates are in seconds, I'm not sure.  See the help for
xdata and timefmt, it should be possible.

Good luck
-- Simon

-- 
Simon Clift                        ssclift at math dot uwaterloo dot ca
Ph.D. Student, Computational Finance
Scientific Computing Group, School of Computer Science
University of Waterloo
Waterloo, Ontario, Canada   N2L 3G1

is there any way to introduce a line with a concrete character while creating 
a file, so that I can plot every piece of file between those characters as an 
individual plot, once above the others?? I mean... I want to save in a file 
several points, of several people. Then I want to compare all those people in 
a graph, so I want to plot each person's respective points in a different 
color and so on.  
Thank you very much if you can help me.

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
 
Hello everyone,

I'm not yet a subscriber to this list, so please send at least a CC of
your answers to me personally.

I have basically the same question as Geoff Low had in his post '
Plotting time formats in gnuplot-py
<http://sourceforge.net/mailarchive/message.php?msg_id=10079214> ' on
2004-11-18 01:45
I used gnuplot.py quite extensively a couple of years ago and I really
loved it, except for the problem that the gnuplot process needed the
'using' keyword when plotting time-series data. As the PlotItems of
that time didn't allow setting the using-keyword I was forced to work
with temporary files which takes away much of the speed and comfort of
having python controlling gnuplot.

Recently I'm again doing more visualization of time-series and I have
tried to utilize gnuplot's rather limited batch-file capabilities
using nested 'call's to achieve my goals. But that still means a lot
of duplication of code, which I would like to avoid.
I have also tried IDL, but I found that gnuplot's defaults make up
much better images and the cusomization is much easier with gnuplot
even though IDL is basically more powerful if you have enough time to
tweak it the way you want (and this is what I don't have, as usual :-) ).

So my question is, if there is any way to trick the gnuplot process
into using python-arrays that contain time-series information without
resorting to temporary files? I would be back to gnuplot and python in
no time :-)

Best regards,



Thomas

- --
_______________________________________________________

Dipl.-Ing Thomas Pfaff, M.Eng.

Dr.-Ing. Karl Ludwig
Beratender Ingenieur
Wasserwirtschaft - Wasserbau
Herrenstr. 14
76133 Karlsruhe

Tel: 0721 / 91251-46
Fax: 0721 / 91251-19

tho...@lu...
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Hello, I have some troubles with Gnuplot. I'm working with python gnuplot.py 
module. I don't know why an error message appears in my screen when trying to 
draw a plot. This is the message:

 Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "graficas.py", line 55
    Gnuplot.plot 'fichero0' with linespoints, 'fichero1' with linespoints
                          ^
SyntaxError: invalid syntax

How must the be the name of the file so that I can call it without problems?? 
when I create these files with python I don't give them any extension since 
it seems not to be necessary. 

I would be also pleased if you could help me with another question: can I 
change names to every point in the axis?? I mean... I want to represent dates 
in the Xaxis. To do so I have previously converted those dates to seconds 
with python since I know the file must contain just numbers. But once I have 
created the files I don't want to see the X axis divided into numbers, but 
into dates, so can I change the names of the divisions of the axis? And in 
case it must be divided into many points.... can I make my graph to move 
horizontally with the help of any kind of bar?is there any way to create it?

Thank you very very much for your help!!
Edurne from Spain.

hi,
i'm using gnuplot to plot waveforms and sonograms under windows.
as i'm having up to 10 plotwindows on the screen it would be nice
to have the possibility to set the positions and sizes of the windows
from py. is it possible and if so, how?

sven.