jim holtman wrote:
> Now take a look at what happens when you convert your dataframe to a matrix:
>
>
>> x <- as.matrix(mydf)
>> str(x)
>>
> ....
> It is a character matrix.
>
>
This is a bit confusing (but deliberate; as.matrix.data.frame explicitly
counts POSIXct as non-numeric):
> mode(as.matrix(mydf)[1,1])
[1] "character"
> mode(as.matrix(mydf[1,1]))
[1] "numeric"
> mode(as.matrix(mydf[1,]))
[1] "character"
> mode(as.matrix(mydf[,1]))
[1] "numeric"
> mode(unlist(mydf[1,]))
[1] "numeric"
> unlist(mydf[1,])
X1 X2 X3 X4 X5
X6 X7
1199835988 1199835988 1199835988 1199835988 1199835988 1199835988
1199835988
X8 X9 X10
1199835988 1199835988 1199835988
And hence also
> sapply(mydf,max)
X1 X2 X3 X4 X5
X6 X7
1199835988 1199835988 1199835988 1199835988 1199835988 1199835988
1199835988
X8 X9 X10
1199835988 1199835988 1199835988
The ticket seems to be
> do.call(c, lapply(mydf,max))
X1
X2 X3
"2008-01-09 00:46:27 CET" "2008-01-09 00:46:27 CET" "2008-01-09 00:46:27
CET"
X4
X5 X6
"2008-01-09 00:46:27 CET" "2008-01-09 00:46:27 CET" "2008-01-09 00:46:27
CET"
X7
X8 X9
"2008-01-09 00:46:27 CET" "2008-01-09 00:46:27 CET" "2008-01-09 00:46:27
CET"
X10
"2008-01-09 00:46:27 CET"
> class(do.call(c,lapply(mydf,max)))
[1] "POSIXt" "POSIXct"
--
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
