[R] data frame with nested data frame

Vadim Ogranovich vogranovich at jumptrading.com
Thu Dec 23 23:06:48 CET 2010


Dear R-users,

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)))
[1] "Names: 1 string mismatch"                                                       "Length mismatch: comparison on first 2 components"
[3] "Component 2: Modes: list, numeric"                                              "Component 2: names for target but not for current"
[5] "Component 2: Attributes: < Modes: list, NULL >"                                 "Component 2: Attributes: < names for target but not for current >"
[7] "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'

> version
               _
platform       i386-pc-mingw32
arch           i386
os             mingw32
system         i386, mingw32
status
major          2
minor          9.1
year           2009
month          06
day            26
svn rev        48839
language       R
version.string R version 2.9.1 (2009-06-26)


Thanks,
Vadim

Note: This email is for the confidential use of the named addressee(s) only and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you are hereby notified that any review, dissemination or copying of this email is strictly prohibited, and to please notify the sender immediately and destroy this email and any attachments.  Email transmission cannot be guaranteed to be secure or error-free.  Jump Trading, therefore, does not make any guarantees as to the completeness or accuracy of this email or any attachments.  This email is for informational purposes only and does not constitute a recommendation, offer, request or solicitation of any kind to buy, sell, subscribe, redeem or perform any type of transaction of a financial product.



More information about the R-help mailing list