#4529: Implement plots with logarithmic scale
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Reporter: ronanpaixao | Owner: ronanpaixao
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-5.1
Component: graphics | Resolution:
Keywords: plot log scale | Work issues: convenience functions
Report Upstream: N/A | Reviewers: Karl-Dieter Crisman
Authors: Punarbasu Purkayastha | Merged in:
Dependencies: #12974 | Stopgaps:
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Comment (by ppurka):
Replying to [comment:45 kcrisman]:
> Sorry for the delay - I only scheduled a couple hours of work this
evening. Tomorrow I will have more time.
No problems. It is better to have a good implementation than to hurry
through a bad one.
> Hey, I just had an idea. Maybe this ticket should be ''only'' about the
ticket description, and then another ticket for adding the "shortcut"
commands like `plot_loglog` or whatever. In which case the current
patches might be enough! (After much testing, of course.) What do you
think?
Actually, there is zero change to be done to the code in `plot` or
`list_plot`, except to add some examples. The only change that the
additional patch will do is make very thin (one-liners) wrappers which
defines the `plot_*` and `list_plot_*` wrappers and pass the correct scale
option to `plot` and `list_plot`. The current consensus from the poll
seems to favor this syntax. In view of this, the patch
[attachment:trac_4529-add_docs_eg_to_some_user_facing_functions.patch]
requires only a renaming of the functions, and some extra examples.
> * We'll eventually want to add some examples (or replace some of these)
with the `plot(...,scale='loglog')` format ones. And definitely to add
some to the file `plot.py`, since that is where a lot of people will look
first for how to get this. '''But''' that can wait until the end, I'll be
happy to do that in a reviewer patch.
We can add exactly similar examples to `plot()` and `list_plot()`.
Currently, since the function is `Graphics.show()`, I decided to write it
as `show(scale=...)` instead of `plot(scale=...)` since the former is more
pertinent.
> * Catching this thing about the flipped `xmin/xmax` and friends is just
a bonus - again, great catch and solution.
> * As to the optional patch, I will think about this some more tomorrow.
I do note that things still "work". For the example you removed `G`, the
example you removed did in fact work, for instance.
Yes I am aware that the examples I provided work. But most of the examples
in the docs of those functions (arc, disk, contour_plot, etc) ''do not''
work out of the box, and we get the "too few ticks" error.
> I'm not sure whether having minor ticks should count as "having two
ticks", especially in the relatively obscure-looking log plot situation.
I'm not even sure why
> {{{
> sage: G.show(scale=('loglog', 2))
> }}}
> works, since there is only one tick on the left!
Yes. That's why I said that the tick checking function is not robust and I
also don't know how to make it robust.
> * Along those lines, your example (changed)
> {{{
> sage: p = list_plot(range(1, 10), plotjoined=True)
> sage: p.show(scale='loglog',base=2)
> }}}
> doesn't show any minor ticks. Is that just how `LogLocator` works, or
is there something wrong?
The minor ticks are generated by passing in multiples of 1/base to the
subs parameter of LogLocator. So, for base 10, you will have ticks at say,
`0.1*10^-1, 0.2*10^-1, ..., 0.9*10^-1, 10^-1`. This is a typical way how
log plots are drawn in all programs (`pyplot.loglog()`, matlab,
mathematica, etc). For `base=2` you can have only one tick `1/2*2^i` but
this is a major tick at `2^(i-1)`. So, you will always see only one major
tick and no minor ticks.
> Obviously at this point we are getting close to nitpicking. I'll try
more tomorrow.
Thanks a lot for the feedback. I am sure I have missed something, so I
look forward to it. :)
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4529#comment:46>
Sage <http://www.sagemath.org>
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