[R] data frame with nested data frame
vogranovich at jumptrading.com
Thu Dec 23 23:06:48 CET 2010
I am somewhat puzzled by how R treats data frames with nested data frames. Below are a couple of examples, maybe someone could help explain what the guiding logic here is.
## construct plain data frame
> z <- data.frame(x=1)
## add a data frame member
> z$y <- data.frame(a=1,b=2)
## puzzle 1: z is apparently different from a straightforward construction of the 'same' object
> all.equal(z, data.frame(x=1,y=data.frame(a=1,b=2)))
 "Names: 1 string mismatch" "Length mismatch: comparison on first 2 components"
 "Component 2: Modes: list, numeric" "Component 2: names for target but not for current"
 "Component 2: Attributes: < Modes: list, NULL >" "Component 2: Attributes: < names for target but not for current >"
 "Component 2: Attributes: < Length mismatch: comparison on first 0 components >" "Component 2: Length mismatch: comparison on first 1 components"
## puzzle 2: could not rbind z
> rbind.data.frame(z, z)
Error in `row.names<-.data.frame`(`*tmp*`, value = c("1", "1")) :
duplicate 'row.names' are not allowed
In addition: Warning message:
non-unique value when setting 'row.names': '1'
system i386, mingw32
svn rev 48839
version.string R version 2.9.1 (2009-06-26)
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