[R] Sandard deviation calculation

[marcos carvajalino]

Yup you're right, after posting i took a better look at the
subsetting, found the problem and post again, my bad...

2009/10/27 Duncan Murdoch <murdoch at stats.uwo.ca>:
> On 27/10/2009 2:58 PM, marcos carvajalino wrote:
>>
>> Dear ms.
>>
>> The most possible reason for this:
>>
>>> Dear all
>>> I am trying to learn R
>>> I was trying to calculate standard deviation
>>> here are the commands and outputs in R
>>>>
>>>> sd(Ht_cm[type=='SD'])[1] 3.283605> sd(Ht_cm[from_treeline=='above'])[1]
>>>> 16.83289> >sd(Ht_cm[type=='SD'][from_treeline=='above'])[1] NA>
>>
>>> the problem is that, i could not understand why the third command could
>>> not give any >result.
>>
>>> please help me out
>>
>>> thanking you
>>
>>> Regard
>>> MS
>>> Nepal
>>
>> is that you're trying to calculate sd over a vector where a NA (Not
>> available) value is contained, that is, you have an empty cell, a
>> different type of data or no data satisfies your condition, try:
>>
>>> sd(Ht_cm[type=='SD'][from_treeline=='above'],na.rm=T)
>>
>> That should do it...
>
> That's legal syntax, but it is very unlikely to be correct.  Hadley gave
> good advice (modulo his typo).
>
> Duncan Murdoch
>



-- 
Marcos Antonio Carvajalino Fernández
Estudiante de Ingeniería Ambiental y Sanitaria
Universidad del Magdalena, Colombia