[R] Odp: R-way to doing this?

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 23.12.2010 05:13:37:

> Dear friends, hope I could be able to explain my problem through 
following
> example. Please consider this:
> 
> 
> 
> > set.seed(1)
> 
> > input <- rnorm(10)
> 
> > input
> 
> [1] -0.6264538  0.1836433 -0.8356286  1.5952808  0.3295078 -0.8204684
> 0.4874291  0.7383247  0.5757814 -0.3053884
> 
> > tag <- vector(length=10)
> 
> 
> 
> for(i in 1:10)
> 
>     #  if there is any ****error**** in evaluating "log(input[i])" (or
> evaluating some function) then tag[i] = 1, otherwise tag[i] = 0 
> 
> 
> 
> Therefore my "tag" vector should like: tag[1]=1, tag[2]=0, tag[3]=1,
> tag[4]=0, tag[5]=0.......
> 
> 
> 
> Actually R returns logarithm of a negative number as NaN, however in 
this
> example please consider R returns error when it encounters logarithm of 
a
> negative number.
> 

I do not understand above sentence well. R returns NaN not error.

For error handling in loop use try or tryCatch.

For simple vectorised function evaluation as log you can use is.* 
evaluation 

is.nan(log(input))*1
[1] 1 0 1 0 0 1 0 0 0 1

ifelse(is.nan(log(input)), 1,0)
 [1] 1 0 1 0 0 1 0 0 0 1

Regards
Petr



> 
> 
> Is there any way to do above task?
> 
> 
> 
> Thanks and regards,
> 
> 
>    [[alternative HTML version deleted]]
> 
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