Re: Bar plot with logarithmic scale on y-axis

[Ben Abbott]

On Mar 24, 2014, at 8:53 AM, Juan Pablo Carbajal <address@hidden> wrote:

> On Mon, Mar 24, 2014 at 12:48 PM, Damian Harty <address@hidden> wrote:
>>> I'd like to plot my data in a bar chart with log scale on the y-axis. 
>>> Here's what I tried:
>> 
>>> h = bar ([1:10]',rand(10,1));
>>> set (gca,'yscale','log');
>> 
>>> The first command produces the expected bar chart. The second command scales
>>> the y-axis as expected, but the bars in the plot get screwed up. Can someone
>>> please help me with this?
>> 
>> I think the plotting algorithm tries to draw the boxes for the bars from 
>> zero and flags a logarithm domain error at this point. Excel handles this 
>> "intuitively" but alas Octave only draws the top of the bar.
>> 
>> I have 3 options to offer:
>> 
>> 1) Edit the code to do what you want (be careful what you wish for)
>> 2) Make a new variable that is the log of your data and plot that on 
>> appropriately annotated scales
>> 3) Plot the data in Excel or similar
>> 
>> 
>> 
>> 
>> CONFIDENTIAL: The information contained in this email communication is 
>> confidential information intended only for the use of the addressee. 
>> Unauthorized use, disclosure or copying of this communication is strictly 
>> prohibited and may be unlawful. If you have received this communication in 
>> error, please notify us immediately by return email and destroy all copies 
>> of this communication, including all attachments.
>> _______________________________________________
>> Help-octave mailing list
>> address@hidden
>> https://mailman.cae.wisc.edu/listinfo/help-octave
> 
> Remember that you can get help using the command
>> help bar
> 
> In this case you will see that the option "basevalue" solves your problem. 
> e.g.
> 
> h = bar ([1:10]',rand(10,1),"basevalue",1e-8);
> set (gca,'yscale','log');

I just checked Matlab.  For log scale Matlab's basevalue is equal to 1.

Looks like a bug.

I filed a bug report.

https://savannah.gnu.org/bugs/index.php?41944

Ben