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
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