Re: pshistogram GMT4.5.11: strange results

On Jan 27, 2014, at 7:20 AM, Sigward Funke <[email protected]> wrote:

> Hi,
> 
> first my questions related to pshistogram: 
> * Could there some influence of rounding and margins of the bins?

Since your values land exactly on the bin borders things may round differently.  Clearly you want centered bins instead (-F).

> * Can I force 0.1 binning centered at 0.5, 0.6, 0,7 ... 1.5, 1.6, 1.7?
Yes -F

> * Or more general: Can I define one margin of the first (or last) bin?
You mean let the first bin cover everything to the left of it and the last everything to the right [or down/up to some specified limit?].  No, but you could add a feature request on gmt.soest.hawaii.edu

I think perhaps pshistogram is backwards when it reports 0.45 etc.  In my thinking, without -F we have bins that go from 0.5 to 0.6, 0.6 to 0.7 and so on, so the bin centers would be 0.55, 0.65, etc. But that is not what is reported.  With -F we should have bins from 0.55 to 0.65, 0.65 to 0.75 etc, with bin centers at 0.6, 0.7 etc.  So perhaps the output coordinate is messed up.  I will check.

-p
> 
> 
> Background: Struggeling with pshistogram I created following script:
> 
> ------- start test_pshistogram.sh ----------
> pshistogram -Io -W0.1 -V <<END
> 1.7  
> 1.4  
> 0.9  
> 0.8  
> 0.8  
> 0.7  
> 0.7  
> 0.6  
> 0.5  
> 0.5  
> 0.5  
> 0.5  
> END
> -------  end test_pshistogram.sh  ----------
> 
> Calling this script I get:
> 
> $
> $ ./test_pshistogram.sh 
> pshistogram: 12 points read
> pshistogram: WARNING: 12 multiple modes found
> pshistogram: Extreme values of the data :	0.5	1.7
> pshistogram: Locations: L2, L1, LMS; Scales: L2, L1, LMS	0.8	0.7	0.6	
> 0.381385035698	0.29652	0.14826
> 
> pshistogram: min/max values are :	0.5	1.7	0	5
> 0.5	5
> 0.6	2
> 0.8	2
> 0.9	1
> 1.3	1
> 1.6	1
> $
> 
> The lines beginning with "pshistogram" fit my expections, but in the table of 
> the last lines I would expect:
> 
> 0.5 4
> 0.6 1
> 0.7 2
> 0.8 2
> 0.9 1
> 1.4 1
> 1.7 1
> 
> Playing with the Option -F the confusion increases. Adding "-F" I get
> 
> 0.45	4
> 0.55	1
> 0.65	2
> 0.75	2
> 0.85	1
> 1.35	1
> 1.65	1
> 
> Despite of the offset of 0.05 this result looks better, but it isn't what I 
> want. Should I add 0.05 to the first column?
> 
> Any hint is welcome!
> 
> Best Regards
> Sigward Funke
> 
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