gnuplot-py-users

[Gnuplot-py-users] Polar plotting?

[Baphijmm <bap...@gm...>]

Hello,

I have just begun to use python at all, much less gnuplot.py; I have to 
say first that so far, this is a great tool and I'm very glad it's out 
there and available.

Now, at the moment I'm having a problem getting the utility to plot a 
polar circle.  Below is the code being used:

g('set terminal x11')
g('set output')
g('set polar')
g('unset border')
g('unset xtics')
g('unset ytics')
g('set size square')
g('set xrange[-2:2]')
g('set yrange[-2:2]')
g.plot(1.7)

It seems perfectly fine until it gets to the actual g.plot() part, where 
it gives me this error:

Traceback (most recent call last):
  File "./pytest", line 83, in <module>
    g.plot(1.7)
  File "/opt/csw/lib/python/site-packages/Gnuplot/_Gnuplot.py", line 
273, in plot
    self._add_to_queue(items)
  File "/opt/csw/lib/python/site-packages/Gnuplot/_Gnuplot.py", line 
243, in _add_to_queue
    self.itemlist.append(PlotItems.Data(item))
  File "/opt/csw/lib/python/site-packages/Gnuplot/PlotItems.py", line 
543, in Data
    utils.write_array(f, set)
  File "/opt/csw/lib/python/site-packages/Gnuplot/utils.py", line 95, in 
write_array
    assert set.shape[0] > 0
IndexError: tuple index out of range

This exact same set of equivalent commands produces a circle of radius 
1.7 in gnuplot.  Am I doing something wrong with the python itself?  The 
documentation is highly sparse, and doesn't mention polar coordinate 
systems at all; as such, I couldn't find the answer there.

Re: [Gnuplot-py-users] Polar plotting?

[Benny M. <ben...@gm...>]

The plot is a built in function working on the Gnuplot.Data, eg:

data[i] = Gnuplot.Data(self.grid_x,
                            self.sol[i],with_='lines',
                            title='Solution at t=%g' %(time))

where sol is a solution over a grid, then eg to plot a number of profiles:

g.title('Concentration profiles')
g.xlabel('x [1e-6 m]')
g.ylabel('Conc  [mol/mm^3]')
g.plot(data[0])
for val in data[1:]:
    g.replot(val)

So it does not work on polar, to do what you want, keep interacting with
gnuplot commands, so:

g('set terminal x11')
> g('set output')
> g('set polar')
> g('unset border')
> g('unset xtics')
> g('unset ytics')
> g('set size square')
> g('set xrange[-2:2]')
> g('set yrange[-2:2]')


and not:

g.plot(1.7)


instead:

g.('plot(1.7)')

Benny

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