Re: [R] na.approx and columns with NA's

From: Gabor Grothendieck <ggrothendieck_at_gmail.com>
Date: Sun, 27 May 2007 14:58:23 -0400

na.approx uses approx and has the same behavior as it. Try this:

> library(zoo)
>
> # test data
> z <- zoo(matrix(1:24, 6))
> z[,2:3] <- NA
> z[1, 2] <- 3
> z[2, 1] <- NA
> z

1 1 3 NA 19
2 NA NA NA 20
3 3 NA NA 21
4 4 NA NA 22
5 5 NA NA 23
6 6 NA NA 24
>
> # TRUE for each column that has more than 1 non-NA
> idx <- colSums(!!z, na.rm = TRUE) > 1
> idx

[1] TRUE FALSE FALSE TRUE
>
> z[,idx] <- na.approx(z[,idx])
> z

1 1 3 NA 19
2 2 NA NA 20
3 3 NA NA 21
4 4 NA NA 22
5 5 NA NA 23
6 6 NA NA 24

On 5/27/07, antonio rodriguez <antonio.raju_at_gmail.com> wrote:
> Hi,
>
> I have a object 'zoo':
>
> dim(zz)
> [1] 720 5551
>
> where some columns only have NA's values (representing land data in a
> sea surface temperature dataset) I find straightforward the use of
> 'na.approx' for individual columns from the zz matrix, but when applied
> to the whole matrix:
>
> zz.approx<-na.approx(zz)
> Erro en approx(along[!na], y[!na], along[na], ...) :
> need at least two non-NA values to interpolate
>
> The message is clear, but how do I could skip those 'full-NA's' columns
> from the interpolation in order to perform the analysis over the columns
> which represent actual data with some NA's values
>
> Best regards,
>
> Antonio
>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Sun 27 May 2007 - 19:11:09 GMT

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