[R] filling small gaps of N/A

[R. Michael Weylandt]

Like I said in my followup, please pass the maxgap argument: i.e.,
na.approx(x, maxgap = 4)

x <- zoo(1:20, Sys.Date() + 1:20)

x[2:4] <- NA # Short run of NA's
x[10:16] <- NA # Long run of NA's

na.approx(x) # All filled in
na.approx(x, maxgap = 4) # Only the short one filled in

Michael

On Tue, Apr 3, 2012 at 10:13 AM, jeff6868
<geoffrey_klein at etu.u-bourgogne.fr> wrote:
> Michael,
>
> First of all, thank you very much for your answer.
> I've read your 2 answers, but I'm not really sure that they corresponds to
> my problem of NAs.
> I'll try to detail you a bit more.
>
> This problem concerns the second part of my program. In the first part, I've
> already created a timeseries object with the library (timeseries). I had to
> delete first all the wrong values in my data and replace it with NAs.
> So my data contains already missing data (NAs), as I have cleaned it before.
>
> The thing is that sometimes I have small gaps of missing data (only 2 or 3
> following) like in "example 1" below:
>
> example 1:
>
> 09/01/2008 12:00      1.93
> 09/01/2008 12:15      3.93
> 09/01/2008 12:30       NA            So here you have a small gap with only
> 2 NAs
> 09/01/2008 12:45       NA
> 09/01/2008 13:00      4.93
> 09/01/2008 13:15      5.93
>
> But sometimes, always in the same file, I have big gaps, such as 10 or more
> NAs following each other like in "example 2" below:
>
> example 2:
>
> 09/01/2008 16:15                2.93
> 09/01/2008 16:30                2.93
> 09/01/2008 16:45                NA
> 09/01/2008 17:00                NA
> 09/01/2008 17:15                NA
> 09/01/2008 17:30                NA
> 09/01/2008 17:45                NA
> 09/01/2008 18:00                NA          So here you have a big gap with more than 10
> NAs following each other
> 09/01/2008 18:15                NA
> 09/01/2008 18:30                NA
> 09/01/2008 18:45                NA
> 09/01/2008 19:00                NA
> 09/01/2008 19:15                NA
> 09/01/2008 19:30                NA
> 09/01/2008 19:45                NA
> 09/01/2008 20:00                NA
> 09/01/2008 20:15                7.93
> 09/01/2008 20:30                7.93
>
> So in the whole same file, I can have sometimes big gaps (2 or 3 NAs),
> sometimes big or very big gaps (10 or 100 NAs following).
>
> The aim of my problem is to apply the function: na.approx(x) of the library
> (zoo) to fill NAs ONLY for small gaps.
>
> If I just do: apply(na.approx(x)), it will fill all the NAs of my data (big
> gaps + small gaps). It's exactly what I DON'T WANT.
>
> My problem is to say to R: " you apply the function (na.approx) to fill NAs
> ONLY if you see 4 NAs maximum following each other (small gaps) (like
> example 1)". "If you see more than 4 NAs following each other (big gaps like
> in example 2), you keep these NAs and you DON'T fill this big gap".
>
> My question is: how can I say this to R? I don't know how to do it.
> Hope I've been understandable this time ^^
> Thanks a lot again for all your answers!
>
>
>
> --
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>
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