Time problems (POSIXct)

Yes, its possible but if you have date data Date class would be the
better choice.  See R News 4/1.
Thanks Gabor,

I suppose that in the example below, ?you can convet Date to POSIXct as
well, can't you?

Best,
Costas

On 20/05/2010 18:08, Gabor Grothendieck wrote:
The warning message does tell you exactly what was wrong. ? You are
trying to merge zoo objects that have two different index classes.
The first is "POSIXct" and the second is "Date" class. ?Next time
please provide your data in reproducible form
as shown here:

library(zoo)
z1<- zoo(1:6, as.Date(c("1950-01-05", "1950-01-06", "1950-01-09",

+ ? "1950-01-10", "1950-01-11", "1950-01-12")))

z2<- zoo(c(16.66, 16.85, 16.93, 16.98, 17.08, 17.03),

+ as.POSIXct(c("1950-01-03, GMT", "1950-01-04, GMT", "1950-01-05, GMT",
+ ? "1950-01-06, GMT", "1950-01-09 GMT", "1950-01-10 GMT")))

merge(z1, z2 = aggregate(z2, as.Date, identity))

? ? ? ? ? ?z1 ? ?z2
1950-01-03 NA 16.66
1950-01-04 NA 16.85
1950-01-05 ?1 16.93
1950-01-06 ?2 16.98
1950-01-09 ?3 17.08
1950-01-10 ?4 17.03
1950-01-11 ?5 ? ?NA
1950-01-12 ?6 ? ?NA

# or
z2.Date<- z2
time(z2.Date)<- as.Date(time(z2.Date))

merge(z1, z2.Date)

? ? ? ? ? ?z1 z2.Date
1950-01-03 NA ? 16.66
1950-01-04 NA ? 16.85
1950-01-05 ?1 ? 16.93
1950-01-06 ?2 ? 16.98
1950-01-09 ?3 ? 17.08
1950-01-10 ?4 ? 17.03
1950-01-11 ?5 ? ? ?NA
1950-01-12 ?6 ? ? ?NA

On Thu, May 20, 2010 at 10:48 AM, Research<risk2009 at ath.forthnet.gr>
?wrote:

Hello,

I have a zoo time series object (say a) ?with the following time
stamp/format

[1] "1950-01-03 GMT" "1950-01-04 GMT" "1950-01-05 GMT" "1950-01-06 GMT"
[5] "1950-01-09 GMT" "1950-01-10 GMT"

and another (say b) with

[1] "1950-01-05" "1950-01-06" "1950-01-09" "1950-01-10" "1950-01-11"
[6] "1950-01-12"

I want to merge these series ? but when I try:

head(merge(a, b ))

? ? ? ? ? ? ? ? ? ?a ? ? ? ? ? ? ? ? ? b
1950-01-03 02:00:00 ? ? ? 16.66 ? NA
1950-01-04 02:00:00 ? ? ? 16.85 ? NA
1950-01-05 02:00:00 ? ? ? 16.93 ? NA
1950-01-06 02:00:00 ? ? ? 16.98 ? NA
1950-01-09 02:00:00 ? ? ? 17.08 ? NA
1950-01-10 02:00:00 ? ? ? 17.03 ? NA
Warning message:
In merge.zoo(a, b) :
?Index vectors are of different classes: POSIXt Date

Anybody can help? ?I tried as.POSIXct(a,tz="GMT") but it doesn't seem to
work....

Many thanks in advance!

Costas
? ? ? ? ? ? ?_
platform ? ? ? i386-pc-mingw32
arch ? ? ? ? ? i386
os ? ? ? ? ? ? mingw32
system ? ? ? ? i386, mingw32
status
major ? ? ? ? ?2
minor ? ? ? ? ?10.1
year ? ? ? ? ? 2009
month ? ? ? ? ?12
day ? ? ? ? ? ?14
svn rev ? ? ? ?50720
language ? ? ? R
version.string R version 2.10.1 (2009-12-14)

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Time problems (POSIXct)

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