[R] Min , Max

[David Winsemius]

On Apr 28, 2012, at 9:54 AM, Jonsson wrote:

> This code bellow will calculate average daily wind  
> speed(measurements are
> taken every three hours).
>
snipped overly complex code not needed to address the semantic error  
below.

> the values are measured in kelvin so i want to convert them to
> degree,therefor I want to subtract all values by 273.15 before  
> talking the
> average or max.... but did not work.In other words, i want this:  
> every value
> is subtracted by 273.15 first ,then do other calculations(Min, Max)Can
> anyone tell me what is wrong.Thanks
>
> tm[ta[i],tb[i]]= round(10 * mean(D[((d-1)*8 + 1:8)-273.15), i])) #  
> wrong

You should not be subtracting the temperature offset within the index  
if your goal was to subtract the same number from each value in a  
matrix. Move it outside the index/extract function. You didn't get an  
error from "[" because it automatically truncated the floating point  
numbers you were passingwhich should have been integer vectors.

  tm[ta[i],tb[i]]= round(10 * mean(D[((d-1)*8 + 1:8)-273.15),  
i]-273.15))

(No effort made to check for the sensibility of the assignment to the  
'tm' matrix.)

Note:
  c(1,2)[2.5]
#[1] 2  No error .... or even a warning.


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David Winsemius, MD
West Hartford, CT