Re: [Gnuplot-py-users] Resolution of Plots

[Michael H. <mh...@al...>]

On 12/09/2013 03:40 PM, Richard B. Langley wrote:
> On Monday, December 9, 2013,343, at 3:47 AM, Michael Haggerty wrote:
>> On 12/08/2013 02:49 PM, Richard Langley wrote:
>>> I have a file of x,y real data pairs with the values to 9 digits of
>>> precision. When I use gnuplot to plot the data directly using, say:
>>> plot 'HHAT3260.csv' using 2:1
>>> I get a detailed plot with the values at their original precision.
>>> However, when I use gnuplot within Python (having read in the file to
>>> float lists x and y) using:
>>> g = Gnuplot.Gnuplot(debug=1)
>>> d = Gnuplot.Data(x, y, with_='points')
>>> g.plot(d)
>>> I get a plot with plotted values rounded or truncated to 7 digits of
>>> precision, it seems. Is there a way to preserve the precision of the
>>> data when using py-gnuplot?
>>
>> Gnuplot.py's default is to treat data as 32-bit floating point numbers.
>> But if you explicitly pass double-precision data to Gnuplot.Data(),
>> then I think it will pass the data to gnuplot with the higher precision.
>> I.e., do something like
>>
>>    d = Gnuplot.Data(
>>        numpy.array(x, dtype=numpy.float64),
>>        numpy.array(y, dtype=numpy.float64),
>>        with_='points',
>>        )

> Thanks, Michael, but, sadly, that did not work.
> -- Richard

Hmm, sorry, I thought I had built something like that in.  If so, it
would have been more then 10 years ago, so I hope you will forgive me :-)

The formatting is done by the function write_array() in the file
utils.py.  The individual elements are formatted using '%s'.  If you
change that to '%r' (in two places) or '%.20g' or something like that, I
think you'll get what you want.  Or, of course, you can always write the
data to a file yourself, similar to how PlotItems.Data() does it.

Michael

-- 
Michael Haggerty
mh...@al...
http://softwareswirl.blogspot.com/