Hi,
I want to create a data frame similar to the following, but greatly scaled up:
df <- data.frame(aaa= c("a","b","c"),
integer(3), integer(3))
names(df)[2:3] <- paste("var",1:2,sep="")
which yields
aaa var1 var2
1 a 0 0
2 b 0 0
3 c 0 0
I would not relish having to paste 'integer(3)' 5000 times :(
So (I figure) there must be a way to do this programmatically, something akin to
exp1 <- paste(rep("integer(3)",2),collapse=',')
which looks like it might work: "integer(3),integer(3)" , as in
the following
df <- data.frame(aaa=xxx, eval(parse(text=exp1)))
but this yields
Error in parse(text = exp1) : <text>:1:11: unexpected ','
1: integer(3),
^
Not sure just why this doesn't work (?parse does not help), but it's not
important right now.
I have used eval and parse in the past, but not in a way similar to what I'm
trying to do now.
exp1 <- rep("integer(3)",2) gives "integer(3)"
"integer(3)"
and upon parse(text=exp1) gives expression(integer(3), integer(3))
which appears to be promising, and does not give an error in the following
df <- data.frame(aaa=xxx, eval(parse(text=exp1)))
but alas, does not give the desired result
aaa eval.parse.text...exp1..
1 a 0
2 b 0
3 c 0
I'm guessing that only the last evaluation of the expression is being
evaluated, which I can understand.
I feel certain that what I want to accomplish can be done programmatically, but
am at a loss as to just how to do that.
Chances are this has been covered before. If so, apologies.
If not, can anyone point me to references with more info than the help pages, or
suggest a solution? :)
Thanks,
Derek
Derek Janszen, PhD
Statistician, Analytics
Precision for Medicine<http://www.precisionformedicine.com/>
8425 Progress Drive, Suite M | Frederick, MD 21701
+1 240 415 6004 office
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> On Apr 4, 2016, at 9:22 AM, Janszen, Derek <derek.janszen at precisionformedicine.com> wrote: > > Hi, > > I want to create a data frame similar to the following, but greatly scaled up: > df <- data.frame(aaa= c("a","b","c"), integer(3), integer(3)) > names(df)[2:3] <- paste("var",1:2,sep="") > which yields > aaa var1 var2 > 1 a 0 0 > 2 b 0 0 > 3 c 0 0 >> setNames( data.frame( rep(list( 1:3), 5) ) , paste0("V", 1:5) )V1 V2 V3 V4 V5 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 Or:> data.frame( c( list( 'a'=letters[1:3] ), rep(list('x'=integer(3) ), 5) ))a x x.1 x.2 x.3 x.4 1 a 0 0 0 0 0 2 b 0 0 0 0 0 3 c 0 0 0 0 0 Just replace the 3's and 5's with a number (possibly delivered via a named numeric vector of length-1) of your choosing. -- David.> I would not relish having to paste 'integer(3)' 5000 times :( > > So (I figure) there must be a way to do this programmatically, something akin to > exp1 <- paste(rep("integer(3)",2),collapse=',') > which looks like it might work: "integer(3),integer(3)" , as in the following > df <- data.frame(aaa=xxx, eval(parse(text=exp1))) > but this yields > > Error in parse(text = exp1) : <text>:1:11: unexpected ',' > > 1: integer(3), > > ^ > > > Not sure just why this doesn't work (?parse does not help), but it's not important right now. > > I have used eval and parse in the past, but not in a way similar to what I'm trying to do now. > > > > exp1 <- rep("integer(3)",2) gives "integer(3)" "integer(3)" > > and upon parse(text=exp1) gives expression(integer(3), integer(3)) > > which appears to be promising, and does not give an error in the following > > df <- data.frame(aaa=xxx, eval(parse(text=exp1))) > > but alas, does not give the desired result > aaa eval.parse.text...exp1.. > 1 a 0 > 2 b 0 > 3 c 0 > > > > > I'm guessing that only the last evaluation of the expression is being evaluated, which I can understand. > > I feel certain that what I want to accomplish can be done programmatically, but am at a loss as to just how to do that. > Chances are this has been covered before. If so, apologies. > If not, can anyone point me to references with more info than the help pages, or suggest a solution? :) > > Thanks, > Derek > > Derek Janszen, PhD > Statistician, Analytics > > Precision for Medicine<http://www.precisionformedicine.com/> > 8425 Progress Drive, Suite M | Frederick, MD 21701 > +1 240 415 6004 office > > > > The information contained in this email and any attachments is confidential and may be subject to copyright or other intellectual property protection. If you are not the intended recipient, you are not authorized to use or disclose this information, and we request that you notify us by reply mail or telephone and delete the original message from your mail system. > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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.David Winsemius Alameda, CA, USA
I think you need to spend some time with an R tutorial or two to learn how to handle such basics yourself. However, if I understand correctly, probably the easiest way to do it is by converting a matrix of 0's to a data frame -- which you shouldn't do at all if you can do your analysis directly with the matrix (it's almost always faster, sometimes considerably so). e.g. adf <- data.frame(matrix(0, nrow=10,ncol=20)) Of course, you may then wish to provide more informative names for your columns via the names() function. Also, I would question whether you need to do any of this in the first place. It is rarely necessary in R to initialize a data frame or matrix. Finally, you should almost never need the eval(parse()) construction, which treats R as a macro language instead of taking advantage of its functional programming paradigm. Again, the of sort thing that good R tutorials can help you with. There are many on the web. Some good recommendations can be found here: https://www.rstudio.com/online-learning/#R HTH, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Mon, Apr 4, 2016 at 9:22 AM, Janszen, Derek <derek.janszen at precisionformedicine.com> wrote:> Hi, > > I want to create a data frame similar to the following, but greatly scaled up: > df <- data.frame(aaa= c("a","b","c"), integer(3), integer(3)) > names(df)[2:3] <- paste("var",1:2,sep="") > which yields > aaa var1 var2 > 1 a 0 0 > 2 b 0 0 > 3 c 0 0 > > I would not relish having to paste 'integer(3)' 5000 times :( > > So (I figure) there must be a way to do this programmatically, something akin to > exp1 <- paste(rep("integer(3)",2),collapse=',') > which looks like it might work: "integer(3),integer(3)" , as in the following > df <- data.frame(aaa=xxx, eval(parse(text=exp1))) > but this yields > > Error in parse(text = exp1) : <text>:1:11: unexpected ',' > > 1: integer(3), > > ^ > > > Not sure just why this doesn't work (?parse does not help), but it's not important right now. > > I have used eval and parse in the past, but not in a way similar to what I'm trying to do now. > > > > exp1 <- rep("integer(3)",2) gives "integer(3)" "integer(3)" > > and upon parse(text=exp1) gives expression(integer(3), integer(3)) > > which appears to be promising, and does not give an error in the following > > df <- data.frame(aaa=xxx, eval(parse(text=exp1))) > > but alas, does not give the desired result > aaa eval.parse.text...exp1.. > 1 a 0 > 2 b 0 > 3 c 0 > > > > > I'm guessing that only the last evaluation of the expression is being evaluated, which I can understand. > > I feel certain that what I want to accomplish can be done programmatically, but am at a loss as to just how to do that. > Chances are this has been covered before. If so, apologies. > If not, can anyone point me to references with more info than the help pages, or suggest a solution? :) > > Thanks, > Derek > > Derek Janszen, PhD > Statistician, Analytics > > Precision for Medicine<http://www.precisionformedicine.com/> > 8425 Progress Drive, Suite M | Frederick, MD 21701 > +1 240 415 6004 office > > > > The information contained in this email and any attachments is confidential and may be subject to copyright or other intellectual property protection. If you are not the intended recipient, you are not authorized to use or disclose this information, and we request that you notify us by reply mail or telephone and delete the original message from your mail system. > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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.