[matplotlib-devel] Re: RE : [Matplotlib-users] Log plot in base b?

[Dominique O. <Dom...@po...>]

Great, this is doing the job nicely, thanks ! I am not very clear as to=20
what the 'subs' argument really does. In your example:

 > #full control
 > gca().set_xscale('log',base=3D100,subs=3D[10,20,50])
 > #Major tick every 16**i, minor tick every subs*16**i

(16 should be 100 right?). There's a major tick at 100, 100^2, 100^3,=20
etc. And you're saying there are minor tick marks at 10*100*i ?!?

What if you'd want tick labels [0, 1, 2, 3, 4, ...] instead of (in base=20
2, say) [1, 2, 4, 8, 16, ...] ? Is that easily done? I tried to obtain=20
it based on the example custom_ticker1.py (in the examples=20
subdirectory), but haven't been successful so far.

Thanks A LOT for the update of axes.py and ticker.py,
Dominique

Gregory Lielens wrote:

> Hi, I though about this too and your message has convinced me it was
> worth spending a few minutes adding this ;-)
> I just patched loglocator and logformater to be able to use arbitrary
> base, and also to use arbitrary "minor" ticks. Well, I put minor betwee=
n
> quotes because Logticker do not really use minor ticks, only discard
> label for ticks that are not integer exponents of base...
> Usage is like this:
> Semilogx(x,y)
>=20
> #compatible with previous usage
> gca().set_xscale('log')=20
> # major tick every 10**i, minor tick every range(2,10)*10**I
>=20
> #change base
> gca().set_xscale('log',base=3D16)
> #Major tick every 16**i, minor tick every range(2,16)*16**i=20
>=20
> #full control
> gca().set_xscale('log',base=3D100,subs=3D[10,20,50])
> #Major tick every 16**i, minor tick every subs*16**i=20
>=20
>=20
> This gives me all the flexibility I need, and I feel it is a step in th=
e
> right direction, but:
>  -maybe a rework of log ticker is needed so that it use minor/major tic=
k
> mechanism? Current mechanism is not as clean as it could, imho
>  -maybe autoscale for loglocator should adjust the base/range to avoid
> excessive ticking (A discussion I had with john, with a zoom out it is
> possible to have very dense ticking)...Not so easy to do though, as sub=
s
> has to be adjusted too if one does not want too many minor ticks, as
> this adjustment is not so easy to do if one want "usefull" minor ticks
> in logscale...
> I thing these 2 points are linked, I would not go to 2 if 1 is not done=
,
> but if one is done (using some kind of linear locator (with autoscale
> capability) on 1 decade for minor ticks, and repeat this minor tick on
> each decade as I have done with my subs, I think we can have a very nic=
e
> framework to have fully automatic and nicely configurable log ticking
> :-)=20
>=20
>=20
> Best regards,
>=20
> Greg.
>=20
> PS: the 2 modified files are included, I made my modif relative to
> CVS...
>=20
>=20
>>-----Message d'origine-----
>>De : mat...@li...=20
>>[mailto:mat...@li...] De la=20
>>part de Dominique Orban
>>Envoy=E9 : mardi 17 ao=FBt 2004 18:57
>>=C0 : mat...@li...
>>Objet : [Matplotlib-users] Log plot in base b?
>>
>>
>>Hi,
>>
>>What would be the easiest way, in matplotlib, to achieve log scaling,=20
>>along the x axis, say, in a base other than 10? I see in axes.py that=20
>>semilog[xy] have LOG10 hardwired. I am using matplotlib 0.60.2.
>>
>>Thanks,
>>Dominique