Re: [R] Comparing transform to with
Gabor,
That's very nice! I like your my.transform much better. Too bad about
the incompatibility. Swapping that out would no doubt break some
existing programs. I love that old joke, God was able to create the
universe in just 6 days only because he didn't have an installed base to
worry about!
Cheers,
Bob
-Original Message-
From: Gabor Grothendieck [mailto:[EMAIL PROTECTED]
Sent: Sunday, September 02, 2007 10:47 AM
To: Muenchen, Robert A (Bob)
Cc: r-help@stat.math.ethz.ch
Subject: Re: [R] Comparing transform to with
Try this version of transform. In the first test we show
it works on your example but we have used the head of the built in
anscombe data set. The second and third show that
it necessarily is incompatible with transform because transform
always looks up variables in DF first whereas my.transform looks
up the computed ones first.
my.transform - function(DF, ...) {
f - function(){}
formals(f) - eval(substitute(as.pairlist(c(alist(...), DF
body(f) - substitute(modifyList(DF, data.frame(...)))
f()
}
# test
a - head(anscombe)
# 1
my.transform(a, sum1 = x1+x2+x3+x4, sum2 = y1+y2+y3+y4, total =
sum1+sum2)
# 2
my.transform(a, y2 = y1, y3 = y2)
# 3
transform(a, y2 = y1, y3 = y2) # different
On 9/1/07, Muenchen, Robert A (Bob) [EMAIL PROTECTED] wrote:
Hi All,
I've been successfully using the with function for analyses and the
transform function for multiple transformations. Then I thought, why
not
use with for both? I ran into problems couldn't figure them out
from
help files or books. So I created a simplified version of what I'm
doing:
rm( list=ls() )
x1-c(1,3,3)
x2-c(3,2,1)
x3-c(2,5,2)
x4-c(5,6,9)
myDF-data.frame(x1,x2,x3,x4)
rm(x1,x2,x3,x4)
ls()
myDF
This creates two new variables just fine
transform(myDF,
sum1=x1+x2,
sum2=x3+x4
)
This next code does not see sum1, so it appears that transform
cannot
see the variables that it creates. Would I need to transform new
variables in a second pass?
transform(myDF,
sum1=x1+x2,
sum2=x3+x4,
total=sum1+sum2
)
Next I'm trying the same thing using with. It doesn't not work but
also does not generate error messages, giving me the impression that
I'm
doing something truly idiotic:
with(myDF, {
sum1-x1+x2
sum2-x3+x4
total - sum1+sum2
} )
myDF
ls()
Then I thought, perhaps one of the advantages of transform is that
it
works on the left side of the equation without using a longer name
like
myDF$sum1. with probably doesn't do that, so I use the longer form
below. It also does not work and generates no error messages.
# Try it again, writing vars to myDF explicitly.
# It generates no errors, and no results.
with(myDF, {
myDF$sum1-x1+x2
myDF$sum2-x3+x4
myDF$total - myDF$sum1+myDF$sum2
} )
myDF
ls()
I would appreciate some advice about the relative roles of these two
functions why my attempts with with have failed.
Thanks!
Bob
=
Bob Muenchen (pronounced Min'-chen), Manager
Statistical Consulting Center
U of TN Office of Information Technology
200 Stokely Management Center, Knoxville, TN 37996-0520
Voice: (865) 974-5230
FAX: (865) 974-4810
Email: [EMAIL PROTECTED]
Web: http://oit.utk.edu/scc,
News: http://listserv.utk.edu/archives/statnews.html
__
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.
__
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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.
Re: [R] Comparing transform to with
Try this version of transform. In the first test we show
it works on your example but we have used the head of the built in
anscombe data set. The second and third show that
it necessarily is incompatible with transform because transform
always looks up variables in DF first whereas my.transform looks
up the computed ones first.
my.transform - function(DF, ...) {
f - function(){}
formals(f) - eval(substitute(as.pairlist(c(alist(...), DF
body(f) - substitute(modifyList(DF, data.frame(...)))
f()
}
# test
a - head(anscombe)
# 1
my.transform(a, sum1 = x1+x2+x3+x4, sum2 = y1+y2+y3+y4, total = sum1+sum2)
# 2
my.transform(a, y2 = y1, y3 = y2)
# 3
transform(a, y2 = y1, y3 = y2) # different
On 9/1/07, Muenchen, Robert A (Bob) [EMAIL PROTECTED] wrote:
Hi All,
I've been successfully using the with function for analyses and the
transform function for multiple transformations. Then I thought, why not
use with for both? I ran into problems couldn't figure them out from
help files or books. So I created a simplified version of what I'm
doing:
rm( list=ls() )
x1-c(1,3,3)
x2-c(3,2,1)
x3-c(2,5,2)
x4-c(5,6,9)
myDF-data.frame(x1,x2,x3,x4)
rm(x1,x2,x3,x4)
ls()
myDF
This creates two new variables just fine
transform(myDF,
sum1=x1+x2,
sum2=x3+x4
)
This next code does not see sum1, so it appears that transform cannot
see the variables that it creates. Would I need to transform new
variables in a second pass?
transform(myDF,
sum1=x1+x2,
sum2=x3+x4,
total=sum1+sum2
)
Next I'm trying the same thing using with. It doesn't not work but
also does not generate error messages, giving me the impression that I'm
doing something truly idiotic:
with(myDF, {
sum1-x1+x2
sum2-x3+x4
total - sum1+sum2
} )
myDF
ls()
Then I thought, perhaps one of the advantages of transform is that it
works on the left side of the equation without using a longer name like
myDF$sum1. with probably doesn't do that, so I use the longer form
below. It also does not work and generates no error messages.
# Try it again, writing vars to myDF explicitly.
# It generates no errors, and no results.
with(myDF, {
myDF$sum1-x1+x2
myDF$sum2-x3+x4
myDF$total - myDF$sum1+myDF$sum2
} )
myDF
ls()
I would appreciate some advice about the relative roles of these two
functions why my attempts with with have failed.
Thanks!
Bob
=
Bob Muenchen (pronounced Min'-chen), Manager
Statistical Consulting Center
U of TN Office of Information Technology
200 Stokely Management Center, Knoxville, TN 37996-0520
Voice: (865) 974-5230
FAX: (865) 974-4810
Email: [EMAIL PROTECTED]
Web: http://oit.utk.edu/scc,
News: http://listserv.utk.edu/archives/statnews.html
__
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.
[R] Comparing transform to with
Hi All,
I've been successfully using the with function for analyses and the
transform function for multiple transformations. Then I thought, why not
use with for both? I ran into problems couldn't figure them out from
help files or books. So I created a simplified version of what I'm
doing:
rm( list=ls() )
x1-c(1,3,3)
x2-c(3,2,1)
x3-c(2,5,2)
x4-c(5,6,9)
myDF-data.frame(x1,x2,x3,x4)
rm(x1,x2,x3,x4)
ls()
myDF
This creates two new variables just fine
transform(myDF,
sum1=x1+x2,
sum2=x3+x4
)
This next code does not see sum1, so it appears that transform cannot
see the variables that it creates. Would I need to transform new
variables in a second pass?
transform(myDF,
sum1=x1+x2,
sum2=x3+x4,
total=sum1+sum2
)
Next I'm trying the same thing using with. It doesn't not work but
also does not generate error messages, giving me the impression that I'm
doing something truly idiotic:
with(myDF, {
sum1-x1+x2
sum2-x3+x4
total - sum1+sum2
} )
myDF
ls()
Then I thought, perhaps one of the advantages of transform is that it
works on the left side of the equation without using a longer name like
myDF$sum1. with probably doesn't do that, so I use the longer form
below. It also does not work and generates no error messages.
# Try it again, writing vars to myDF explicitly.
# It generates no errors, and no results.
with(myDF, {
myDF$sum1-x1+x2
myDF$sum2-x3+x4
myDF$total - myDF$sum1+myDF$sum2
} )
myDF
ls()
I would appreciate some advice about the relative roles of these two
functions why my attempts with with have failed.
Thanks!
Bob
=
Bob Muenchen (pronounced Min'-chen), Manager
Statistical Consulting Center
U of TN Office of Information Technology
200 Stokely Management Center, Knoxville, TN 37996-0520
Voice: (865) 974-5230
FAX: (865) 974-4810
Email: [EMAIL PROTECTED]
Web: http://oit.utk.edu/scc,
News: http://listserv.utk.edu/archives/statnews.html
__
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] Comparing transform to with
Muenchen, Robert A (Bob) wrote:
Hi All,
I've been successfully using the with function for analyses and the
transform function for multiple transformations. Then I thought, why not
use with for both? I ran into problems couldn't figure them out from
help files or books. So I created a simplified version of what I'm
doing:
rm( list=ls() )
x1-c(1,3,3)
x2-c(3,2,1)
x3-c(2,5,2)
x4-c(5,6,9)
myDF-data.frame(x1,x2,x3,x4)
rm(x1,x2,x3,x4)
ls()
myDF
This creates two new variables just fine
transform(myDF,
sum1=x1+x2,
sum2=x3+x4
)
This next code does not see sum1, so it appears that transform cannot
see the variables that it creates. Would I need to transform new
variables in a second pass?
transform(myDF,
sum1=x1+x2,
sum2=x3+x4,
total=sum1+sum2
)
Next I'm trying the same thing using with. It doesn't not work but
also does not generate error messages, giving me the impression that I'm
doing something truly idiotic:
with(myDF, {
sum1-x1+x2
sum2-x3+x4
total - sum1+sum2
} )
myDF
ls()
Then I thought, perhaps one of the advantages of transform is that it
works on the left side of the equation without using a longer name like
myDF$sum1. with probably doesn't do that, so I use the longer form
below. It also does not work and generates no error messages.
# Try it again, writing vars to myDF explicitly.
# It generates no errors, and no results.
with(myDF, {
myDF$sum1-x1+x2
myDF$sum2-x3+x4
myDF$total - myDF$sum1+myDF$sum2
} )
myDF
ls()
I would appreciate some advice about the relative roles of these two
functions why my attempts with with have failed.
Yes, transform() calculates all its new values, then assigns to the
given names. This is expedient, but it has the drawback that new
variables are not usable inside the expressions. A possible alternative
implementation would be equivalent to a series of nested calls to
transform, which of course you could also do manually:
transform(
transform(myDF,
sum1=x1+x2,
sum2=x3+x4
),
total=sum1+sum2
)
The problem with with() on data frames and lists is that, like the
eval family of functions, _converts_ the object to an environment, and
then evaluates the expression in the converted environment. The
environment is temporary, so assignments to it get lost. The current
development sources has a new (experimental) function within() which is
like with(), but stores any modified variables back. (This is very
recent and may or may not make it to 2.6.0).
--
O__ Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
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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.
