[R] Sort problem with merge (again)

[Gabor Grothendieck]

If you want it to act like a date store it as a Date:

dx <- as.Date(c("1970-04-04","1970-08-11","1970-10-18")) ###
x <- c(9,10,11)
ch <- data.frame(Date=dx,X=x)

dy <- as.Date(c("1970-06-04","1970-08-11","1970-08-18")) ###
y <- c(109,110,111)
sp <- data.frame(Date=dy,Y=y)

merge(ch, sp, all = TRUE)

By the way you might consider using zoo objects here:

library(zoo)
chz <- zoo(x, dx)
spz <- zoo(y, dy)
merge(chz, spz)

See:
vignette("zoo")

On 9/25/06, Bruce LaZerte <bdl at fwr.on.ca> wrote:
> # R version 2.3.1 (2006-06-01) Debian Linux "testing"
>
> # Is the following behaviour a bug, feature or just a lack of
> # understanding on my part? I see that this was discussed here
> # last March with no apparent resolution.
>
> d <- as.factor(c("1970-04-04","1970-08-11","1970-10-18"))
> x <- c(9,10,11)
> ch <- data.frame(Date=d,X=x)
>
> d <- as.factor(c("1970-06-04","1970-08-11","1970-08-18"))
> y <- c(109,110,111)
> sp <- data.frame(Date=d,Y=y)
>
> df <- merge(ch,sp,all=TRUE,by="Date")
> # the rows with dates missing all ch vars are tacked on the end.
> # the rows with dates missing all sp vars are sorted in with
> # the row with a date with vars from both ch and sp
> # is.ordered(df$Date) returns FALSE
>
> # The rows of df are not sorted as they should be as sort=TRUE
> # is the default. Adding sort=TRUE does nothing.
> # So try this:
> # dd <- df[order(df$Date),]
> # But that doesn't work.
> # Nor does sort(df$Date)
> # But sort(as.vector(df$Date)) does work.
> # As does order(as.vector(df$Date)), so this works:
> dd <- df[order(as.vector(df$Date)),]
> # ?????
>
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