From: Hsiu-Khuern Tang <hsiu-khuern.tang_at_hp.com>

Date: Fri 13 Oct 2006 - 23:38:47 GMT

R-help@stat.math.ethz.ch 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. Received on Sat Oct 14 09:46:20 2006

Date: Fri 13 Oct 2006 - 23:38:47 GMT

Reading the list of changes for R version 2.4.0, I was happy to see that the
row names of dataframes can be stored compactly (as the integer n when
row.names(df) is 1:n).

help(row.names) contains this paragraph:

Row names of the form '1:n' for 'n > 2' are stored internally in a compact form, which might be seen by calling 'attributes' but never via 'row.names' or 'attr(x, "row.names")'.

I am unable to get attributes(x)$row.names to return just nrow(x). Am I misreading the documentation? Does "might be seen" mean "possibly in some future version of R" in this case?

> (x <- as.data.frame(matrix(1:9, nrow=3)))

V1 V2 V3

1 1 4 7

2 2 5 8

3 3 6 9

> attributes(x)$row.names

[1] 1 2 3

> row.names(x) <- seq(len=nrow(x))

> attributes(x)$row.names

[1] 1 2 3

Best,

Hsiu-Khuern.

R-help@stat.math.ethz.ch 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. Received on Sat Oct 14 09:46:20 2006

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