On 03/07/2019 12:42 p.m., Jeff Newmiller wrote:
Dummy columns do have some drawbacks though, if you find yourself working with
large data frames. The dummy columns waste memory and time as compared to
either reorganizing columns after the `within` or using separate sequential
`with` expressions as I previously suggested. I think mutate avoids this
overhead also.
I think mutate() has only a very small advantage over within(). Neither
one of them is flexible about the order of columns in the final result.
In the OPs example, mutate creates the variables in the desired order,
but it would be no better if the desired order had been a, c, b, because
b is needed for the calculation of c, so it would be created first.
Eric's suggestion
within(df, {b<-a*2; c<-b*3})[c("a","b","c")]
is the best so far, though I'd probably write it as
within(df, {b<-a*2; c<-b*3})[, c("a","b","c")]
just to avoid confusing my future self and make clear that I'm talking
about specifying an order for the columns.
And if you really, really want everything to happen within the call,
just create the variables in the reverse order to what you want, e.g.
within(df, {c <- a; b<-a*2; c<-b*3})
but to me that is a lot less clear than Eric's solution.
Duncan Murdoch
On July 3, 2019 8:25:32 AM PDT, Eric Berger <ericjber...@gmail.com> wrote:
Nice suggestion, Richard.
On Wed, Jul 3, 2019 at 4:28 PM Richard O'Keefe <rao...@gmail.com>
wrote:
Why not set all the new columns to dummy values to get the order you
want and then set them to their final values in the order that works
for that?
On Thu, 4 Jul 2019 at 00:12, Kevin Thorpe <kevin.tho...@utoronto.ca>
wrote:
On Jul 3, 2019, at 3:15 AM, Sebastien Bihorel <
sebastien.biho...@cognigencorp.com> wrote:
Hi,
The within function can be used to modify data.frames (among
other
objects). One can even provide multiple expressions to modify the
data.frame by more than one expression. However, when new variables
are
created, they seem to be inserted in the data.frame in the opposite
order
they were declared:
df <- data.frame(a=1)
within(df, {b<-a*2; c<-b*3})
a c b
1 1 6 2
Is there a way to insert the variables in an order consistent
with the
order of declaration (ie, a, b, c)?
One way is to use mutate() from the dplyr package.
Thanks
Sebastien
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.
--
Kevin E. Thorpe
Head of Biostatistics, Applied Health Research Centre (AHRC)
Li Ka Shing Knowledge Institute of St. Michael's
Assistant Professor, Dalla Lana School of Public Health
University of Toronto
email: kevin.tho...@utoronto.ca Tel: 416.864.5776 Fax:
416.864.3016
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.
[[alternative HTML version deleted]]
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.
[[alternative HTML version deleted]]
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.
