R help - Jan 2014 - How to detect a sequence of NA values?

Hi,
Try:
rl <- rle(is.na(a))
?max(rl$lengths[rl$values])
#[1] 3


A.K.


Hi, 

I'd like to detect whether a vector contains a sequence?of NA values of a
certain length. So, for example, if I have a vector a =
c(1,NA,NA,4,NA,NA,NA,5); how can I find what the longest sequence of NAs is (in
this case 3)?

Note that this is different from simply summing the number of NA values in the
vector (which would be 5 in this case)...

Thanks for your help !

Another way:

a = c(1,NA,NA,4,3,NA,NA,NA,NA,5)

# find position of the non-NAs in the vector
pos = which(!is.na(a))

# this calculates the length by taking the differences between the
non-NA positions.
diff(pos)-1

#get the max
max(diff(pos)-1)

Richard

On Tue, Jan 7, 2014 at 7:36 PM, arun <smartpink111 at yahoo.com>
wrote:
> Hi,
> Try:
> rl <- rle(is.na(a))
>  max(rl$lengths[rl$values])
> #[1] 3
>
>
> A.K.
>
>
> Hi,
>
> I'd like to detect whether a vector contains a sequence of NA values of
a certain length. So, for example, if I have a vector a >
c(1,NA,NA,4,NA,NA,NA,5); how can I find what the longest sequence of NAs is (in
this case 3)?
>
> Note that this is different from simply summing the number of NA values in
the vector (which would be 5 in this case)...
>
> Thanks for your help !
>
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