From: <a9804814_at_unet.univie.ac.at>

Date: Wed, 05 Mar 2008 20:56:27 +0100

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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. Received on Wed 05 Mar 2008 - 20:03:20 GMT

Date: Wed, 05 Mar 2008 20:56:27 +0100

Hello,

I am an advanced user of R. Recently I found out that apparently I do not fully understand vectors and lists fully Take this code snippet:

T = c("02.03.2008 12:23", "03.03.2008 05:54") Times = strptime(T, "%d.%m.%Y %H:%M")

Times # OK class(Times) # OK is.list(Times) # sort of understand and not understand that length(Times) # 9 ??? why is it length(Times[1]) ??

Times[1] # OK

Times[[1]] # Wrong

so Times is a vector-style thing of a non-atomic type. What puzzles me is first that is.list returns true, and more importantly that the length-query returns the length of the first object of that apparent list and not how many elements are contained (i.e., I would have expected 2 as result - and I do not know what syntax to use in order to get the 2).

Moreover, if the whole thing is part of a data.frame:

DFTimes = as.data.frame(Times)

dim(DFTimes)

length(DFTimes$Times) # OK, 2

then everything is as expected.

Could anyone please clearify why is.list returns true and why length in the first example returns 9 ? Is it that c() makes a list if the objects to be concatenated are not representable directly by atomic types ?

thanks,

Thomas

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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. Received on Wed 05 Mar 2008 - 20:03:20 GMT

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