Re: [R] Equivalent to a BY command in SAS
Thanks all. I will try to use both tapply and by, and have no idea how I missed the by function. Thanks again. -- View this message in context: http://www.nabble.com/Equivalent-to-a-BY-command-in-SAS-tp16670452p16676280.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org 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] Equivalent to a BY command in SAS
On 4/14/2008 7:30 AM, zerfetzen wrote: Thanks all. I will try to use both tapply and by, and have no idea how I missed the by function. Thanks again. One problem with both of those arises if you are subsetting on several columns. They will do the calculations for all combinations of all columns, even if only a few combinations of levels are present in your dataset. This can make the calculation take up a large amount of memory. I wrote the sparseby function to handle this case; it is in the reshape package. Duncan Murdoch __ R-help@r-project.org 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] Equivalent to a BY command in SAS
You might also take a look at the doBy package. On Apr 14, 2008, at 7:30 AM, zerfetzen wrote: Thanks all. I will try to use both tapply and by, and have no idea how I missed the by function. Thanks again. _ Professor Michael Kubovy University of Virginia Department of Psychology USPS: P.O.Box 400400Charlottesville, VA 22904-4400 Parcels:Room 102Gilmer Hall McCormick RoadCharlottesville, VA 22903 Office:B011+1-434-982-4729 Lab:B019+1-434-982-4751 Fax:+1-434-982-4766 WWW:http://www.people.virginia.edu/~mk9y/ [[alternative HTML version deleted]] __ R-help@r-project.org 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] Equivalent to a BY command in SAS
Hi, I'm very new to R and absolutely love it. Does anyone know how to use something in R that functions like a BY command in SAS? For example, let's say you have a variable x, and you want to see the mean. Easy... mean(x) But what if you want to see the mean of x conditional on another discrete variable? My best attempts so far are something like... mean(x, y_cat=1) ...which of course doesn't work. I have downloaded plenty of R user guides that are very informative, but am not seeing much on detailed descriptives or data manipulation (for my life, I can't figure out how to sort an attached data frame, but that's another issue). Thanks. -- View this message in context: http://www.nabble.com/Equivalent-to-a-BY-command-in-SAS-tp16670452p16670452.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org 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] Equivalent to a BY command in SAS
On Sun, Apr 13, 2008 at 7:36 PM, zerfetzen [EMAIL PROTECTED] wrote: Hi, I'm very new to R and absolutely love it. Does anyone know how to use something in R that functions like a BY command in SAS? For example, let's say you have a variable x, and you want to see the mean. Easy... mean(x) But what if you want to see the mean of x conditional on another discrete variable? My best attempts so far are something like... Using the built-in dataset 'CO2' : # compute the mean 'conc' for every level of 'Plant' tapply(CO2$conc, CO2$Plant, FUN=mean) Qn1 Qn2 Qn3 Qc1 Qc3 Qc2 Mn3 Mn2 Mn1 Mc2 Mc3 Mc1 435 435 435 435 435 435 435 435 435 435 435 435 ?tapply for details ?by for more details Dylan mean(x, y_cat=1) ...which of course doesn't work. I have downloaded plenty of R user guides that are very informative, but am not seeing much on detailed descriptives or data manipulation (for my life, I can't figure out how to sort an attached data frame, but that's another issue). Thanks. -- View this message in context: http://www.nabble.com/Equivalent-to-a-BY-command-in-SAS-tp16670452p16670452.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org 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@r-project.org 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] Equivalent to a BY command in SAS
Le dim. 13 avr. à 22:36, zerfetzen a écrit : Hi, I'm very new to R and absolutely love it. Does anyone know how to use something in R that functions like a BY command in SAS? For example, let's say you have a variable x, and you want to see the mean. Easy... mean(x) But what if you want to see the mean of x conditional on another discrete variable? My best attempts so far are something like... mean(x, y_cat=1) ...which of course doesn't work. I have downloaded plenty of R user guides that are very informative, but am not seeing much on detailed descriptives or data manipulation (for my life, I can't figure out how to sort an attached data frame, but that's another issue). Thanks. You didn't give much detail about what exactly you want to do (have a look at the Posting Guide), but... perhaps by() will do what you what. See ?by . Bye! --- Vincent Goulet, Associate Professor École d'actuariat Université Laval, Québec [EMAIL PROTECTED] http://vgoulet.act.ulaval.ca __ R-help@r-project.org 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] Equivalent to a BY command in SAS
On 14/04/2008, at 2:36 PM, zerfetzen wrote:
Hi,
I'm very new to R and absolutely love it. Does anyone know how to use
something in R that functions like a BY command in SAS?
For example, let's say you have a variable x, and you want to see
the mean.
Easy...
mean(x)
But what if you want to see the mean of x conditional on another
discrete
variable? My best attempts so far are something like...
mean(x, y_cat=1)
...which of course doesn't work. I have downloaded plenty of R
user guides
that are very informative, but am not seeing much on detailed
descriptives
or data manipulation (for my life, I can't figure out how to sort an
attached data frame, but that's another issue). Thanks.
set.seed(42)
x - rnorm(100)
y - sample(letters[1:3],100,TRUE)
by(x,y,mean)
INDICES: a
[1] 0.1089523
INDICES: b
[1] -0.2253035
INDICES: c
[1] 0.2997985
Or:
tapply(x,y,mean)
a b c
0.1089523 -0.2253035 0.2997985
cheers,
Rolf Turner
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