# [R-SIG-Finance] Combine two incomplete zoo object (with NAs) in one zoo series

Gabor Grothendieck ggrothendieck at gmail.com
Thu Apr 1 15:40:22 CEST 2010

ifelse returns plain vectors.  Instead, try the following which
replaces the data portion of zz with the ifelse value:

# 1
zz <- z[,1]
zz[] <- ifelse(is.na(z[,1]), z[,2], z[,1])

or this one line version:

# 1a
zz <- replace(z[,1], TRUE, ifelse(is.na(z[,1]), z[,2], z[,1]))

or this:

# 2
zz <- zoo(ifelse(is.na(z[,1]), z[,2], z[,1]), time(z))

or this which avoids ifelse altogether:

# 3
zz <- z[,1]
zz[is.na(zz)] <- z[is.na(zz), 2]

or this one line version of that:

# 3a
zz <- replace(z[,1], is.na(z[,1]), z[is.na(z[,1]), 2])

or this which also avoids ifelse and uses rollapply with if ... else

# 4
zz <- rollapply(z, 1, function(x) if (is.na(x[1])) x[2] else x[1],
by.column = FALSE)

On Thu, Apr 1, 2010 at 9:12 AM, Pierre Lapointe <pierrelap at gmail.com> wrote:
> Hello I have two times series for the same asset. Unfortunately, the series
> with the most history has been discontinued. I want to combine the old
> series with the new one in a new zoo object. I tried combining them using
> ifelse, but the result is a vector, not a zoo object. In other words, I lost
> the dates in the process.
>
> How do I get the result in a zoo object?
>
> Here's my attempt:
>
>
>
> #build series for reproducible example
>
> z <- zoo(matrix(1:20,ncol=2),
>
>     as.Date(c("1992-01-10", "1992-01-17", "1992-01-24", "1992-01-31",
>
>       "1992-02-07", "1992-02-14", "1992-02-21", "1992-02-28", "1992-03-06",
>
>       "1992-03-13")))
>
> z[1:5,1] <-NA
>
> z[8:10,2] <-NA
>
>
>
> #initial series with imcompletes
>
> z
>
>
>
> #my function
>
> bc.combine <-function(imcomplete.1,fill.with.2){
>
> res <-ifelse(!is.na(imcomplete.1),imcomplete.1,fill.with.2)
>
> return(res)
>
> }
>
>
>
> #two zoo objects as inputs but the result is a vector
>
> bc.combine(z[,2,drop=F],z[,1,drop=F])
>
>
>
>      [,1]
>
>  [1,]   11
>
>  [2,]   12
>
>  [3,]   13
>
>  [4,]   14
>
>  [5,]   15
>
>  [6,]   16
>
>  [7,]   17
>
>  [8,]    8
>
>  [9,]    9
>
> [10,]   10
>
>        [[alternative HTML version deleted]]
>
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