#4529: Implement plots with logarithmic scale
--------------------------------------------------------------+-------------
       Reporter:  ronanpaixao                                 |         Owner:  
ronanpaixao                               
           Type:  enhancement                                 |        Status:  
needs_review                              
       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, Punarbasu Purkayastha
        Authors:  Punarbasu Purkayastha, Karl-Dieter Crisman  |     Merged in:  
                                          
   Dependencies:  #12974                                      |      Stopgaps:  
                                          
--------------------------------------------------------------+-------------
Changes (by ppurka):

  * status:  needs_work => needs_review
  * reviewer:  Karl-Dieter Crisman => Karl-Dieter Crisman, Punarbasu
               Purkayastha


Old description:

> Attached is a patch which introduces log scale to `Graphics()` class.
>
> Depends on #12974.
>
> Apply
>  * [attachment:trac_4529-add-log-scale.patch]
>  * [attachment:trac_4529-single-tick.patch]
>  * [attachment:trac_4529-docs-and-funcs.patch]
>  * [attachment:trac_4529-more-doc.patch]
>
> Old instructions:
>
> Apply the following patches in the specified order. `SAGE_ROOT` is the
> directory where the sage installation is present.
> {{{
> cd SAGE_ROOT/devel/sage
> ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
> attachment/ticket/12974/trac_12974-fix_graphics_attributes.patch
> ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
> attachment/ticket/12974/trac_12974-refactor.patch
> ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
> attachment/ticket/12974/trac_12974-reorder_some_arguments.patch
> ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
> attachment/ticket/12974/trac_12974-whitespace_cleanup.patch
> ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
> attachment/ticket/4529/trac_4529-add_logscale_to_Graphics.2.patch
> ../../sage -b
> }}}
>
> Optionally, also apply patch which checks that there are enough ticks
> when using log scale, but which makes us lose some functionality.
> {{{
> ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
> attachment/ticket/4529/trac_4529-check_for_single_tick.patch
> ../../sage -b
> }}}
>
> ----
> '''OLD DISCUSSION BELOW :)'''
>
> Currently plot() has no option to use logarithmic scales.
>
> One workaround is to use matplotlib directly, with its semilogy(),
> semilogx() and loglog() functions, but that wouldn't produce plots with
> the customisations implemented in sage.
> Another workaround is messing with the plot figure like:
>
> {{{
> #!python
> import pylab
> p=plot(x,marker='.')
> f=pylab.figure()
> f.gca().set_xscale('log')
> p.save(figure=f)
> }}}
>
> But that creates two problems:
>
>  * The first problem is that the adaptive choosing of points just
> considers linear scale, so the points get too much spaced apart in the
> beginning of the plot and too close in the end.
>  * The second problem relates to the axis, which, for the same reason,
> isn't located right.
>
> Also, this requires the user to know how to deal with figures, which is
> not directly exposed by sage.
>
> There are some possibilities to fix that:
>  1. Make plot() detect if the figure changes the scales and modify the
> adaptive algorithm and the axis codes accordingly
>  2. Create a kwarg to tell plot() to implement the scale-change
> internally
>  3. Create other functions to use loglog(), semilogx() and semilogy()
>  4. Many (or all) of the above together, since they aren't mutually
> exclusive
>
> From what I noticed, Mathematica implements the separate functions way,
> but it may be better to fix the issue in plot() itself and if the other
> functions are wanted, just make it so that they call plot() with the
> correct arguments

New description:

 Attached is a patch which introduces log scale to `Graphics()` class.

 Depends on #12974.

 Apply
  * [attachment:trac_4529-add-log-scale.patch]
  * [attachment:trac_4529-single-tick.patch]
  * [attachment:trac_4529-docs-and-funcs.patch]
  * [attachment:trac_4529-more-doc.patch]
  * [attachment:trac_4529-typo_fixes.patch]

 Old instructions:

 Apply the following patches in the specified order. `SAGE_ROOT` is the
 directory where the sage installation is present.
 {{{
 cd SAGE_ROOT/devel/sage
 ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
 attachment/ticket/12974/trac_12974-fix_graphics_attributes.patch
 ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
 attachment/ticket/12974/trac_12974-refactor.patch
 ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
 attachment/ticket/12974/trac_12974-reorder_some_arguments.patch
 ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
 attachment/ticket/12974/trac_12974-whitespace_cleanup.patch
 ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
 attachment/ticket/4529/trac_4529-add-log-scale.patch
 ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
 attachment/ticket/4529/trac_4529-single-tick.patch
 ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
 attachment/ticket/4529/trac_4529-docs-and-funcs.patch
 ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
 attachment/ticket/4529/trac_4529-more-doc.patch
 ../../sage -hg qimport -P http://trac.sagemath.org/sage_trac/raw-
 attachment/ticket/4529/trac_4529-typo_fixes.patch
 ../../sage -b
 }}}

 ----
 '''OLD DISCUSSION BELOW :)'''

 Currently plot() has no option to use logarithmic scales.

 One workaround is to use matplotlib directly, with its semilogy(),
 semilogx() and loglog() functions, but that wouldn't produce plots with
 the customisations implemented in sage.
 Another workaround is messing with the plot figure like:

 {{{
 #!python
 import pylab
 p=plot(x,marker='.')
 f=pylab.figure()
 f.gca().set_xscale('log')
 p.save(figure=f)
 }}}

 But that creates two problems:

  * The first problem is that the adaptive choosing of points just
 considers linear scale, so the points get too much spaced apart in the
 beginning of the plot and too close in the end.
  * The second problem relates to the axis, which, for the same reason,
 isn't located right.

 Also, this requires the user to know how to deal with figures, which is
 not directly exposed by sage.

 There are some possibilities to fix that:
  1. Make plot() detect if the figure changes the scales and modify the
 adaptive algorithm and the axis codes accordingly
  2. Create a kwarg to tell plot() to implement the scale-change internally
  3. Create other functions to use loglog(), semilogx() and semilogy()
  4. Many (or all) of the above together, since they aren't mutually
 exclusive

 From what I noticed, Mathematica implements the separate functions way,
 but it may be better to fix the issue in plot() itself and if the other
 functions are wanted, just make it so that they call plot() with the
 correct arguments

--

Comment:

 Added the typo fixes. I am good with your changes. So, it requires your
 review (as if you haven't reviewed enough already!) ;)

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4529#comment:52>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
and MATLAB

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