Hi all,
I'm plotting data which extent, in x, from -1000 to 1000. But I'm only
interested in the values between x = -1 and 0.
I also want to plot on an x log scale. But since the x-values are negative,
I cannot use xscale("log"). I can use xscale("symlog") though and this is
the behaviour I want.
Unfortunately, "symlog" seems to be broken. I cannot use the linthreshx
argument with a value of less then 2 (the default?). But since I'm
interested in x values from -1 to 0, I have to use that argument and set it
to something like 1e-5 or even smaller.
If I set linthreshx to something smaller then 1, the plot breaks. Here is a
simple example, taken from
http://stackoverflow.com/questions/3305865/what-is-the-difference-between-log-and-symlog
> import numpy
> from matplotlib import pyplot
>
> # Enable interactive mode
> pyplot.ion()
>
> # Draw the grid lines
> pyplot.grid(True)
>
> # Numbers from -50 to 50, with 0.1 as step
> xdomain = numpy.arange(-50,50, 0.1)
>
> # Plots a simple linear function 'f(x) = x'
> pyplot.plot(xdomain, xdomain)
> # Plots 'sin(x)'
> pyplot.plot(xdomain, numpy.sin(xdomain))
>
> pyplot.xscale('symlog', linthreshx=0.1)
>
The problem seems to be that, on the x-axis, 0 is actually 10^0 = 1, not 0.
Putting something smaller then 1 will make the line go back and the axis
values are wrong (when hovering with the mouse and getting the x value).
I might not be using the right tool though, but how to achieve what I want?
I want the x axis to look like:
-10^2 -10^1 -10^0 -10^-1 -10^-2 -10^-3 ... [up to my
defined minimum exponent] ... 10^-3 10^-2 10^-1 10^0 10^1
10^2
Thank you
Nicolas
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