Saving dates in a matrix ("origin must be supplied") with r - r

Question

I am writing my bachelor thesis and I have not much experience with r so far.
My problem is that my dates which I made with this commands :
t<-strptime(x, "%d.%m.%Y %H.%M")
don't work anymore when I save them in a matrix with the other information on those specific dates.
I am a bit confused because it works just fine when I don't put them in a matrix like this t[1:10]
But that happens as soon as I try to save them in a matrix
matrix1<-matrix(c(t,v2,v3,v4),nrow=length(v2))
Fehler in as.POSIXct.numeric(X[[i]], ...) : 'origin' muss angegeben werden
It's German but it means origin must be supplied.
Any ideas what I have to do to fix it? I am a bit frustrated :)

Answer 1

Roland is right. You can't have Posixlt objects in a matrix. What you can do is save those dates as numeric timestamps in the matrix and convert them back to dates while accessing
Converting to numeric timestamp:
>date<- as.numeric(as.POSIXct("2014-02-16 2:13:46 UTC",origin="01-01-1970"))
>date
[1] 1392545626
Then save those timestamps in a matrix as you do and to convert it back to date, use the above command again without converting it into a numeric.

Answer 2

t (terrible name by the way, easily confused with the t function) is a POSIXlt object, which internally is a list. First you should check, what c(t,v2,v3,v4) returns (I don't know how v2 etc are defined).
Then we can look into the documentation in help("matrix"):
data
an optional data vector (including a list or expression vector). Non-atomic classed R objects are coerced by as.vector and all attributes discarded.
The important bit is "all attributes discarded". This is what you get if you discard the attributes (which include the class attribute) of a POSIXlt object:
x <- strptime(c("2016-05-09 12:00:00", "2016-05-09 13:00:00"), format = "%Y-%m-%d %H:%M:%S")
attributes(x) <- NULL
print(x)
# [[1]]
# [1] 0 0
#
# [[2]]
# [1] 0 0
#
# [[3]]
# [1] 12 13
#
# [[4]]
# [1] 9 9
#
# [[5]]
# [1] 4 4
#
# [[6]]
# [1] 116 116
#
# [[7]]
# [1] 1 1
#
# [[8]]
# [1] 129 129
#
# [[9]]
# [1] 1 1
#
# [[10]]
# [1] "CEST" "CEST"
#
# [[11]]
# [1] NA NA
A matrix can't contain POSIXlt objects (or any objects, i.e., anything with an explicit class).