On Fri, Jul 17, 2009 at 5:15 PM, Paul Ray<paul....@nrl.navy.mil> wrote:
>
>
> Ryan Krauss-2 wrote:
>>
>> RTFM:
>>
>> plot(t,y, drawstyle='steps-post')
>>
>>
>
> Actually, 'steps-pre' (which is the default) and 'steps-post' seem to have
> swapped definitions.
> Here is what the docs say:
> *where*: [ 'pre' | 'post' | 'mid' ]
> If 'pre', the interval from x[i] to x[i+1] has level y[i]
> If 'post', that interval has level y[i+1]
> If 'mid', the jumps in *y* occur half-way between the
> *x*-values.
>
> In fact both the default behavior and what you get with steps-pre are what
> SHOULD happen with steps-post. And steps-post (as you point out) does what
> should be the default behavior and that of steps-pre.
>
> I have filed a bug report on this, since it is very important that this work
> as expected. As the original poster pointed out, this used to work
> correctly but recently seems to have gotten broken.
I am looking first at the behavior of plot with the drawstyle property
set -- let's make sure this is correct before turning to the steps
command, which just uses plot with the drawstyle set -- here is my
test code
import numpy as np
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(111)
a = np.array([1,2,3,4,5])
styles = 'default' , 'steps' , 'steps-pre' , 'steps-mid' , 'steps-post'
styles = 'steps' , 'steps-pre'
for ls in styles:
ax.plot(a, ls=ls, label=ls, lw=2)
ax.legend(loc='upper left')
plt.show()
pre causes the step to rise on the x[i], post causes it to rise on
x[i+1] and mid in the middle. This seems like the correct behavior.
So it does look like the docstring for 'step' is incorrect, and I've
changed it to read
*where*: [ 'pre' | 'post' | 'mid' ]
If 'pre', the interval from x[i] to x[i+1] has level y[i+1]
If 'post', that interval has level y[i]
If 'mid', the jumps in *y* occur half-way between the
JDH
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