On Thu, 15 Nov 2007, Andrew Hoskins wrote:
> Hi,
>
> I have a data frame with two columns of data, one an indexing column
> and the other a data column. My issue is, this data frame is
> incomplete and there are missing lines. I want to know how I can
> find and add data into these missing lines. See example below
You could use a "zoo" series (from the "zoo" package) which provides
infrastructure for indexed observations. With your example data:
data <- data.frame(index = c(1:4, 6:10),
data = c(1.5,4.3,5.6,6.7,7.1,12.5,14.5,16.8,3.4))
you can create a series
z <- zoo(data$data, data$index)
end extend it to the grid 1:10
z <- merge(zoo(,1:10), z)
which then has an NA at index 5. Then you could use linear interpolation
to replace that NA
na.approx(z)
or replace it with some other number
z[is.na(z)] <- 42
See vignette("zoo", package = "zoo") for more details.
Z
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