Re: [R] How to see if row names of a dataframe are stored compactly
Try this: > class(attributes(x)$row.names) [1] "integer" > rownames(x) <- as.character(rownames(x)) > class(attributes(x)$row.names) [1] "character" On 10/13/06, Hsiu-Khuern Tang <[EMAIL PROTECTED]> wrote: > 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)$row.names > [1] 1 2 3 > > Best, > Hsiu-Khuern. > > __ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] How to see if row names of a dataframe are stored compactly
Hi Gabor,
* On Fri 07:59PM, 13 Oct 2006, Gabor Grothendieck ([EMAIL PROTECTED]) wrote:
> Try this:
>
> >class(attributes(x)$row.names)
> [1] "integer"
> >rownames(x) <- as.character(rownames(x))
> >class(attributes(x)$row.names)
> [1] "character"
Yes, but this doesn't show that row.names was stored as a _single_
integer (3) instead of a vector of integers (1:3).
Reading the changes again:
The internal storage of row.names = 1:n just records 'n', for
efficiency with very long vectors.
The "row.names" attribute must be a character or integer
vector, and this is now enforced by the C code.
I think row.names is always _printed_ as a vector. I had misinterpreted the
help(row.names) paragraph in my original posting to mean that the internal
storage can be revealed by attributes(x, "row.names"). That paragraph implies
that attributes(x)$row.names and attr(x, "row.names") can have different
classes, but I can't create such an example.
I did this experiment:
> n <- 1
> x <- as.data.frame(matrix(seq(len=2*n), nrow=n))
> head(x)
V1V2
1 1 10001
2 2 10002
3 3 10003
4 4 10004
5 5 10005
6 6 10006
> class(attributes(x)$row.names)
[1] "integer"
> save(x, file="x1", compress=FALSE)
> row.names(x) <- 2:(n+1)
> class(attributes(x)$row.names)
[1] "integer"
> save(x, file="x2", compress=FALSE)
> subset(file.info(c("x1", "x2")), select=size)
size
x1 80205
x2 120197
The difference in size is about nrow(x) * 4 bytes. I think this shows that 1:n
was stored compactly as a single integer but 2:(n+1) was not.
> On 10/13/06, Hsiu-Khuern Tang <[EMAIL PROTECTED]> wrote:
> >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)$row.names
> >[1] 1 2 3
> >
> >Best,
> >Hsiu-Khuern.
> >
> >__
> >R-help@stat.math.ethz.ch mailing list
> >https://stat.ethz.ch/mailman/listinfo/r-help
> >PLEASE do read the posting guide
> >http://www.R-project.org/posting-guide.html
> >and provide commented, minimal, self-contained, reproducible code.
> >
Best,
Hsiu-Khuern.
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] How to see if row names of a dataframe are stored compactly
Take a look with 'dput' and you will see the difference:
> row.names(x) <- 1:n
> dput(x)
structure(list(V1 = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10), V2 = c(11,
12, 13, 14, 15, 16, 17, 18, 19, 20)), .Names = c("V1", "V2"), row.names = c(NA,
10), class = "data.frame")
> row.names(x) <- 2:(n+1)
> dput(x)
structure(list(V1 = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10), V2 = c(11,
12, 13, 14, 15, 16, 17, 18, 19, 20)), .Names = c("V1", "V2"), row.names = c(2,
3, 4, 5, 6, 7, 8, 9, 10, 11), class = "data.frame")
>
'row.names' is different.
On 10/13/06, Hsiu-Khuern Tang <[EMAIL PROTECTED]> wrote:
> Hi Gabor,
>
> * On Fri 07:59PM, 13 Oct 2006, Gabor Grothendieck ([EMAIL PROTECTED]) wrote:
> > Try this:
> >
> > >class(attributes(x)$row.names)
> > [1] "integer"
> > >rownames(x) <- as.character(rownames(x))
> > >class(attributes(x)$row.names)
> > [1] "character"
>
> Yes, but this doesn't show that row.names was stored as a _single_
> integer (3) instead of a vector of integers (1:3).
>
> Reading the changes again:
>
>The internal storage of row.names = 1:n just records 'n', for
>efficiency with very long vectors.
>
>The "row.names" attribute must be a character or integer
>vector, and this is now enforced by the C code.
>
> I think row.names is always _printed_ as a vector. I had misinterpreted the
> help(row.names) paragraph in my original posting to mean that the internal
> storage can be revealed by attributes(x, "row.names"). That paragraph implies
> that attributes(x)$row.names and attr(x, "row.names") can have different
> classes, but I can't create such an example.
>
> I did this experiment:
>
> > n <- 1
> > x <- as.data.frame(matrix(seq(len=2*n), nrow=n))
> > head(x)
> V1V2
> 1 1 10001
> 2 2 10002
> 3 3 10003
> 4 4 10004
> 5 5 10005
> 6 6 10006
> > class(attributes(x)$row.names)
> [1] "integer"
> > save(x, file="x1", compress=FALSE)
> > row.names(x) <- 2:(n+1)
> > class(attributes(x)$row.names)
> [1] "integer"
> > save(x, file="x2", compress=FALSE)
> > subset(file.info(c("x1", "x2")), select=size)
> size
> x1 80205
> x2 120197
>
> The difference in size is about nrow(x) * 4 bytes. I think this shows that
> 1:n
> was stored compactly as a single integer but 2:(n+1) was not.
>
> > On 10/13/06, Hsiu-Khuern Tang <[EMAIL PROTECTED]> wrote:
> > >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)$row.names
> > >[1] 1 2 3
> > >
> > >Best,
> > >Hsiu-Khuern.
> > >
> > >__
> > >R-help@stat.math.ethz.ch mailing list
> > >https://stat.ethz.ch/mailman/listinfo/r-help
> > >PLEASE do read the posting guide
> > >http://www.R-project.org/posting-guide.html
> > >and provide commented, minimal, self-contained, reproducible code.
> > >
>
> Best,
> Hsiu-Khuern.
>
> __
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem you are trying to solve?
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] How to see if row names of a dataframe are stored compactly
* On Fri 10:14PM, 13 Oct 2006, jim holtman ([EMAIL PROTECTED]) wrote:
> Take a look with 'dput' and you will see the difference:
>
> >row.names(x) <- 1:n
> >dput(x)
> structure(list(V1 = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10), V2 = c(11,
> 12, 13, 14, 15, 16, 17, 18, 19, 20)), .Names = c("V1", "V2"), row.names =
> c(NA,
> 10), class = "data.frame")
> >row.names(x) <- 2:(n+1)
> >dput(x)
> structure(list(V1 = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10), V2 = c(11,
> 12, 13, 14, 15, 16, 17, 18, 19, 20)), .Names = c("V1", "V2"), row.names =
> c(2,
> 3, 4, 5, 6, 7, 8, 9, 10, 11), class = "data.frame")
> >
>
> 'row.names' is different.
So it is! Thank you! This also explains why the n x 2 dataframe became
larger by exactly (n-2) * 4 bytes when row.names changed from 1:n to
2:(n+1).
> On 10/13/06, Hsiu-Khuern Tang <[EMAIL PROTECTED]> wrote:
> >Hi Gabor,
> >
> >* On Fri 07:59PM, 13 Oct 2006, Gabor Grothendieck
> >([EMAIL PROTECTED]) wrote:
> >> Try this:
> >>
> >> >class(attributes(x)$row.names)
> >> [1] "integer"
> >> >rownames(x) <- as.character(rownames(x))
> >> >class(attributes(x)$row.names)
> >> [1] "character"
> >
> >Yes, but this doesn't show that row.names was stored as a _single_
> >integer (3) instead of a vector of integers (1:3).
> >
> >Reading the changes again:
> >
> > The internal storage of row.names = 1:n just records 'n', for
> > efficiency with very long vectors.
> >
> > The "row.names" attribute must be a character or integer
> > vector, and this is now enforced by the C code.
> >
> >I think row.names is always _printed_ as a vector. I had misinterpreted
> >the
> >help(row.names) paragraph in my original posting to mean that the internal
> >storage can be revealed by attributes(x, "row.names"). That paragraph
> >implies
> >that attributes(x)$row.names and attr(x, "row.names") can have different
> >classes, but I can't create such an example.
> >
> >I did this experiment:
> >
> >> n <- 1
> >> x <- as.data.frame(matrix(seq(len=2*n), nrow=n))
> >> head(x)
> > V1V2
> >1 1 10001
> >2 2 10002
> >3 3 10003
> >4 4 10004
> >5 5 10005
> >6 6 10006
> >> class(attributes(x)$row.names)
> >[1] "integer"
> >> save(x, file="x1", compress=FALSE)
> >> row.names(x) <- 2:(n+1)
> >> class(attributes(x)$row.names)
> >[1] "integer"
> >> save(x, file="x2", compress=FALSE)
> >> subset(file.info(c("x1", "x2")), select=size)
> >size
> >x1 80205
> >x2 120197
> >
> >The difference in size is about nrow(x) * 4 bytes. I think this shows
> >that 1:n
> >was stored compactly as a single integer but 2:(n+1) was not.
> >
> >> On 10/13/06, Hsiu-Khuern Tang <[EMAIL PROTECTED]> wrote:
> >> >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)$row.names
> >> >[1] 1 2 3
> >> >
> >> >Best,
> >> >Hsiu-Khuern.
> >> >
> >> >__
> >> >R-help@stat.math.ethz.ch mailing list
> >> >https://stat.ethz.ch/mailman/listinfo/r-help
> >> >PLEASE do read the posting guide
> >> >http://www.R-project.org/posting-guide.html
> >> >and provide commented, minimal, self-contained, reproducible code.
> >> >
> >
> >Best,
> >Hsiu-Khuern.
> >
> >__
> >R-help@stat.math.ethz.ch mailing list
> >https://stat.ethz.ch/mailman/listinfo/r-help
> >PLEASE do read the posting guide
> >http://www.R-project.org/posting-guide.html
> >and provide commented, minimal, self-contained, reproducible code.
> >
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem you are trying to solve?
Best,
Hsiu-Khuern.
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] How to see if row names of a dataframe are stored compactly
On Fri, 13 Oct 2006, Hsiu-Khuern Tang wrote: > Reading the list of changes for R version 2.4.0, I was happy to see that the > row names of dataframes can be stored compactly (as the integer n when > row.names(df) is 1:n). > > help(row.names) contains this paragraph: > >Row names of the form '1:n' for 'n > 2' are stored internally in a >compact form, which might be seen by calling 'attributes' but never >via 'row.names' or 'attr(x, "row.names")'. > > I am unable to get attributes(x)$row.names to return just nrow(x). Am I > misreading the documentation? Definitely. It does not say the 'compact form' is 'just nrow(x)', does it? (It is not.) > Does "might be seen" mean "possibly in some > future version of R" in this case? It is not intended that the user ever sees the compact form from R code (it can be seen from C code and also by deparsing), but there were circumstances under which attributes() would show it (but no longer, I believe). >> (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 But see what dump() gives you on that object. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UKFax: +44 1865 272595 __ 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.
Re: [R] How to see if row names of a dataframe are stored compactly
On Fri, 13 Oct 2006, jim holtman wrote:
> Take a look with 'dput' and you will see the difference:
>
>> row.names(x) <- 1:n
>> dput(x)
> structure(list(V1 = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10), V2 = c(11,
> 12, 13, 14, 15, 16, 17, 18, 19, 20)), .Names = c("V1", "V2"), row.names =
> c(NA,
> 10), class = "data.frame")
>> row.names(x) <- 2:(n+1)
>> dput(x)
> structure(list(V1 = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10), V2 = c(11,
> 12, 13, 14, 15, 16, 17, 18, 19, 20)), .Names = c("V1", "V2"), row.names = c(2,
> 3, 4, 5, 6, 7, 8, 9, 10, 11), class = "data.frame")
>>
>
> 'row.names' is different.
Unfortunately, dput() does not give an accurate representation of these
objects: see the warnings on its help page. That is why I mention dump()
not dput() in my reply.
--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UKFax: +44 1865 272595
__
R-help@stat.math.ethz.ch mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
