Statistics Reloaded.

Willem Ferguson willemferguson at zoology.up.ac.za
Wed Jul 19 12:34:13 PDT 2017


On 19/07/2017 18:45, Tomaz Canabrava wrote:
> Hey people,
>
> I'll have one week to work on subsurface because of Akademy, without 
> work or wife interference :)
> So I really think I'll be able to do something good there.
>
> About the mockups - they are good for desktop but they don't take into 
> account mobile.
> but I'll try to do that.
>
> Tomaz
Tomaz,
That would be great. There is one issue we discussed that was not 
finalised, the number of bars in each of the histograms. You could 
initially use a fixed scheme and I or someone else could adapt it 
afterwards to be more flexible without UI intervention. Alternatively, 
here is a (sort of) algorithm that is likely to work to calculate the 
number of bars. Maybe you have your own ideas, then please ignore all of 
this.

# For each histogram:
# -------------------
binvalue = {1.0, 2.0, 2.5, 5.0, 10.0, 20.0}
Find minimum and maximum values of data to be graphed
range = maximum-minimum
BinSize = binvalue with size just > (range/10)
# e.g. if (range/10 == 3) then BinSize = 5;
# with our testdata (range/10=5.6969) then BinSize=10
Startvalue = largest multiple of BinSize just < minimum

In case that my help you, I attach a LibreOffice spreadsheet that uses 
this algorithm on a dataset of 54 values (the blue column).
Ignore the multiplier value. A histogram (red bars) representing these 
values is also shown. Unfortunately LibreOffice does not place the 
numbers below the graph in the correct places.
Basically this uses part of the calculations one would do anyway to draw 
a histogram. Only difference is that we dynamically determine BinSize 
and Startvalue based on the chracteristics of the data.
I attach an image if what that histogram should look like if all labels 
were written correctly. The bars can be wider and touching or narrower 
like in the attached jpg file. I personally prefer wider bars.

I hope this is understandable.

Kind regards,
willem




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