Re: [R] R2 always increases as variables are added?
On 5/21/07, Alberto Monteiro [EMAIL PROTECTED] wrote: Paul Lynch wrote: I don't think it makes sense to compare models with and without an intercept term. (Also, I don't know what the point of using a model without an intercept term would be, but that is probably just my ignorance.) Suppose that you are 100% sure that the intercept term is zero, or so insignifantly small as not to matter. For example, if you are measuring the density of some material, and you determine a lot of pairs (mass, volume), you know that mass = density * volume, with intercept zero. In that case, you are 100% sure that the intercept *should* be zero, but you aren't 100% sure that the measurements have a best fit with intercept zero. There could have been some systematic error that is throwing things off. It seems safer to leave the intercept in and let the data show that the intercept is insignificantly small. However, I don't really know enough to know whether that is always the best approach. (And given that R provides a facility for excluding the intercept, I suspect there must be some good reason for doing so in some circumstances.) -- Paul Lynch Aquilent, Inc. National Library of Medicine (Contractor) __ 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] R2 always increases as variables are added?
Junjie, First, a disclaimer: I am not a statistician, and have only taken one statistics class, but I just took it this Spring, so the concepts of linear regression are relatively fresh in my head and hopefully I will not be too inaccurate. According to my statistics textbook, when selecting variables for a model, the intercept term is always present. The variables under consideration do not include the constant 1 that multiplies the intercept term. I don't think it makes sense to compare models with and without an intercept term. (Also, I don't know what the point of using a model without an intercept term would be, but that is probably just my ignorance.) Similarly, the formula you were using for R**2 seems to only be useful in the context of a standard linear regression (i.e., one that includes an intercept term). As your example shows, it is easy to construct a fit (e.g. y = 10,000,000*x) so that SSR SST if one is not deriving the fit from the regular linear regression process. --Paul On 5/19/07, 李俊杰 [EMAIL PROTECTED] wrote: I know that -1 indicates to remove the intercept term. But my question is why intercept term CAN NOT be treated as a variable term as we place a column consited of 1 in the predictor matrix. If I stick to make a comparison between a model with intercept and one without intercept on adjusted r2 term, now I think the strategy is always to use another definition of r-square or adjusted r-square, in which r-square=sum(( y.hat)^2)/sum((y)^2). Am I in the right way? Thanks Li Junjie 2007/5/19, Paul Lynch [EMAIL PROTECTED]: In case you weren't aware, the meaning of the -1 in y ~ x - 1 is to remove the intercept term that would otherwise be implied. --Paul On 5/17/07, 李俊杰 [EMAIL PROTECTED] wrote: Hi, everybody, 3 questions about R-square: -(1)--- Does R2 always increase as variables are added? -(2)--- Does R2 always greater than 1? -(3)--- How is R2 in summary(lm(y~x-1))$r.squared calculated? It is different from (r.square=sum((y.hat-mean (y))^2)/sum((y-mean(y))^2)) I will illustrate these problems by the following codes: -(1)--- R2 doesn't always increase as variables are added x=matrix(rnorm(20),ncol=2) y=rnorm(10) lm=lm(y~1) y.hat=rep(1*lm$coefficients,length(y)) (r.square=sum((y.hat-mean(y))^2)/sum((y-mean(y))^2)) [1] 2.646815e-33 lm=lm(y~x-1) y.hat=x%*%lm$coefficients (r.square=sum((y.hat-mean(y))^2)/sum((y-mean(y))^2)) [1] 0.4443356 This is the biggest model, but its R2 is not the biggest, why? lm=lm(y~x) y.hat=cbind(rep(1,length(y)),x)%*%lm$coefficients (r.square=sum((y.hat-mean(y))^2)/sum((y-mean(y))^2)) [1] 0.2704789 -(2)--- R2 can greater than 1 x=rnorm(10) y=runif(10) lm=lm(y~x-1) y.hat=x*lm$coefficients (r.square=sum((y.hat-mean(y))^2)/sum((y-mean(y))^2)) [1] 3.513865 -(3)--- How is R2 in summary(lm(y~x-1))$r.squared calculated? It is different from (r.square=sum((y.hat-mean (y))^2)/sum((y-mean(y))^2)) x=matrix(rnorm(20),ncol=2) xx=cbind(rep(1,10),x) y=x%*%c(1,2)+rnorm(10) ### r2 calculated by lm(y~x) lm=lm(y~x) summary(lm)$r.squared [1] 0.9231062 ### r2 calculated by lm(y~xx-1) lm=lm(y~xx-1) summary(lm)$r.squared [1] 0.9365253 ### r2 calculated by me y.hat=xx%*%lm$coefficients (r.square=sum((y.hat-mean(y))^2)/sum((y-mean(y))^2)) [1] 0.9231062 Thanks a lot for any cue:) -- Junjie Li, [EMAIL PROTECTED] Undergranduate in DEP of Tsinghua University, [[alternative HTML version deleted]] __ 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. -- Paul Lynch Aquilent, Inc. National Library of Medicine (Contractor) -- Junjie Li, [EMAIL PROTECTED] Undergranduate in DEP of Tsinghua University, -- Paul Lynch Aquilent, Inc. National Library of Medicine (Contractor) __ 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] Plotting data with a fitted curve
Suppose you have a vector of data in x and response values in y. How do you plot together both the points (x,y) and the curve that results from the fitted model, if the model is not y ~ x, but a higher order polynomial, e.g. y~poly(x,2)? (In other words, abline doesn't work for this case.) Thanks, --Paul -- Paul Lynch Aquilent, Inc. National Library of Medicine (Contractor) __ 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] Vector indexing question
Suppose you have 4 related vectors: a.id-c(1:25, 1:25, 1:25) a.vals - c(101:175)# same length as a.id (the values for those IDs) a.id.levels - c(1:25) a.id.ratings - rep(letters[1:5], times=5)# same length as a.id.levels What I would like to do is specify a rating from a.ratings (e.g. e), get the vector of corresponding IDs from a.id.levels (via a.id.levels[a.id.ratings=='e']) and then somehow use those IDs in a.id to get the corresponding values from a.vals. I think I can probably write a loop to construct of a vector of ratings of the same length as a.id so that the ratings match the ID, and then go from there. Is there a better way? Perhaps using factors or levels or something? Thanks, --Paul -- Paul Lynch Aquilent, Inc. National Library of Medicine (Contractor) __ 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] Vector indexing question
Adai-- Thanks a lot! This is just what I was looking for. I was almost sure there had to be a neat of doing this. Bert-- Thanks for the tip. Marc-- Not quite, although your solution works fine for the case I gave. What I had in mind for a.id was an arbitrary sequence of the numbers in the range [1,25], of length 75, though I was not savvy enough with R to express that succinctly. You spotted a shortcut that I hadn't reallized I was introducing. Thanks all for your help! --Paul On 3/29/07, Adaikalavan Ramasamy [EMAIL PROTECTED] wrote: Sounds like you have two different tables and are trying to mine one based on the other. Try ref - data.frame( levels = 1:25, ratings = rep(letters[1:5], times=5) ) db - data.frame( vals=101:175, levels=c(1:25, 1:25, 1:25) ) levels.of.interest - ref$levels[ ref$rating==a ] db$vals[ which(db$levels %in% levels.of.interest) ] [1] 101 106 111 116 121 126 131 136 141 146 151 156 161 166 171 OR a much more intuitive way is to merge both tables and proceeding as out - merge( db, ref, by=levels, all.x=TRUE ) out - out[ order(out$val), ] # little cleanup subset( out, ratings==a ) # ignore the rownames levels vals ratings 1 1 101 a 16 6 106 a 31 11 111 a 46 16 116 a 61 21 121 a 3 1 126 a 17 6 131 a 32 11 136 a 47 16 141 a 62 21 146 a 2 1 151 a 18 6 156 a 33 11 161 a 48 16 166 a 63 21 171 a Then you can do cool things using the apply() family like tapply( out$vals, out$ratings, mean ) a b c d e 136 137 138 139 140 Check out %in%, merge and apply. Regards, Adai Paul Lynch wrote: Suppose you have 4 related vectors: a.id-c(1:25, 1:25, 1:25) a.vals - c(101:175)# same length as a.id (the values for those IDs) a.id.levels - c(1:25) a.id.ratings - rep(letters[1:5], times=5)# same length as a.id.levels What I would like to do is specify a rating from a.ratings (e.g. e), get the vector of corresponding IDs from a.id.levels (via a.id.levels[a.id.ratings=='e']) and then somehow use those IDs in a.id to get the corresponding values from a.vals. I think I can probably write a loop to construct of a vector of ratings of the same length as a.id so that the ratings match the ID, and then go from there. Is there a better way? Perhaps using factors or levels or something? Thanks, --Paul -- Paul Lynch Aquilent, Inc. National Library of Medicine (Contractor) __ 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] Fitting a line to a qqplot's points?
I've made some normal plots of my data using qqplot, and now I would like to fit a line to the points on the plot and check the correlation coefficient to have a more objective measure of how straight the line is. Is there a simple way of doing that? (I'm still pretty new to R.) Thanks, --Paul -- Paul Lynch Aquilent, Inc. National Library of Medicine (Contractor) __ 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] Connecting R-help and Google Groups?
This morning I tried to see if I could find the r-help mailing list on Google Groups, which has an interface that I like. I found three Google Groups (The R Project for Statistical Computing, rproject, and rhelp) but none of them are connected to the r-help list. Is there perhaps some reason why it wouldn't be a good thing for there to be a connected Google Group? I think it should be possible to set things up so that a post to the Google Group goes to the r-help mailing list, and vice-versa. Also, does anyone know why the three existing R Google Groups failed to get connected to r-help? It might require some action on the part of the r-help list administrator. Thanks, --Paul -- Paul Lynch Aquilent, Inc. National Library of Medicine (Contractor) __ 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] Connecting R-help and Google Groups?
Well, I don't see what danger could arise from the fact that Google Groups is owned by a company. Google Groups provides access to all of usenet, plus many mailing lists (e.g. the ruby-talk mailing list for Ruby programmers). They don't control any of the newgroups or mailing lists that they provide access to. It is a free service, supported by advertising. As for the issue of whether there might be future access problems (e.g. if Google goes bankrupt, which currently seems unlikely) R users would still have access to the r-help list through the means that they have now. I am not recommending replacing any of the current means of access to the r-help list; I am just asking about adding an additional means of access. --Paul On 3/14/07, Bert Gunter [EMAIL PROTECTED] wrote: I know nothing about Google Groups, but FWIW, I think it would be most unwise for R/CRAN to hook up to **any** commercially sponsored web portals. Future changes in their policies, interfaces,or access conditions may make them inaccessible or unfreindly to R users. So long as we have folks willing and able to host and maintain our lists as part of the CRAN infrastructure, CRAN maintains control. I think this is wise and prudent. I am happy to be educated to the contrary if I misunderstand how this would work. Bert Gunter Genentech Nonclinical Statistics South San Francisco, CA 94404 650-467-7374 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Lynch Sent: Wednesday, March 14, 2007 8:48 AM To: R-help@stat.math.ethz.ch Subject: [R] Connecting R-help and Google Groups? This morning I tried to see if I could find the r-help mailing list on Google Groups, which has an interface that I like. I found three Google Groups (The R Project for Statistical Computing, rproject, and rhelp) but none of them are connected to the r-help list. Is there perhaps some reason why it wouldn't be a good thing for there to be a connected Google Group? I think it should be possible to set things up so that a post to the Google Group goes to the r-help mailing list, and vice-versa. Also, does anyone know why the three existing R Google Groups failed to get connected to r-help? It might require some action on the part of the r-help list administrator. Thanks, --Paul -- Paul Lynch Aquilent, Inc. National Library of Medicine (Contractor) __ 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. -- Paul Lynch Aquilent, Inc. National Library of Medicine (Contractor) __ 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] Simplest question ever...
I'm not sure this is the most efficient, but how about: diag(m[a,b]) ? On 3/1/07, yoo [EMAIL PROTECTED] wrote: Let's say i have a = c(1, 4, 5) b = c(2, 6, 7) and i have matrix m, what's an efficient way of access m[1, 2], m[4, 6], m[5, 7] like of course m[a, b] = is not going to do, but what's an expression that will allow me to have that list? Thanks! -- View this message in context: http://www.nabble.com/Simplest-question-ever...-tf3329894.html#a9258932 Sent from the R help mailing list archive at Nabble.com. __ 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] integrate over polygon
I'm still pretty ignorant about R, but I think it might be possible to work out an algorithm using cross products. First you would want to subdivide the polygon into convex polygons. I haven't tried to do that before, but it looks like it might be possible by looking at the sign of cross products of vectors between vertices. (In other words, pick a vertex, and then start working your way around the polygon and pay attention to the sign of cross products of vectors from the starting vertex to successive vertices.) Once you have convex polygons, you can calculate the area using cross products of vectors from some point (e.g. the origin) to adjacent vertices of the polygon. I think that probably most computer graphics texts would have such an algorithm. How to implement that in R is not something I can answer, but it doesn't sound hard. --Paul On 2/14/07, Haiyong Xu [EMAIL PROTECTED] wrote: Hi there, I want to integrate a function over an irregular polygon. Is there any function which can implement this easily? Otherwise, I am thinking of divide the polygon into very small rectangles and use adapt to approximate it. Do you have any suggestions to get the fine division? Any advice is appreciated. Haiyong __ 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] integrate over polygon
Oops. I just re-read your message and saw you were trying to integrate a function over a polygon, not calculate its area. I'm sorry I didn't read more carefully. --Paul On 2/15/07, Paul Lynch [EMAIL PROTECTED] wrote: I'm still pretty ignorant about R, but I think it might be possible to work out an algorithm using cross products. First you would want to subdivide the polygon into convex polygons. I haven't tried to do that before, but it looks like it might be possible by looking at the sign of cross products of vectors between vertices. (In other words, pick a vertex, and then start working your way around the polygon and pay attention to the sign of cross products of vectors from the starting vertex to successive vertices.) Once you have convex polygons, you can calculate the area using cross products of vectors from some point (e.g. the origin) to adjacent vertices of the polygon. I think that probably most computer graphics texts would have such an algorithm. How to implement that in R is not something I can answer, but it doesn't sound hard. --Paul On 2/14/07, Haiyong Xu [EMAIL PROTECTED] wrote: Hi there, I want to integrate a function over an irregular polygon. Is there any function which can implement this easily? Otherwise, I am thinking of divide the polygon into very small rectangles and use adapt to approximate it. Do you have any suggestions to get the fine division? Any advice is appreciated. Haiyong __ 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] R book advice
I'm looking for a book for someone completely ignorant of statistics who wishes to learn both statistics and R. I've found three possibilities, one by Verzani (Using R for Introductory Statistics), one by Crawley (Statistics: An Introduction using R), and one by Dalgaard (Introductory Statistics with R). Do these books have different emphases, perspectives, or strengths? Should I just pick one at random and buy it? Thanks, --Paul __ 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] make check failure, internet.Rout.fail, Error in strsplit
Thanks for giving it a try. It is very odd that you got Content-Length when I am getting Content-length. I just tried curl (I had been using telnet to port 80) and I got the same (error causing) length result: curl --head http://www.stats.ox.ac.uk/pub/datasets/csb/ch11b.dat HTTP/1.1 200 OK Date: Tue, 13 Feb 2007 16:10:41 GMT Server: Apache/2.0.40 (Red Hat Linux) Last-Modified: Fri, 19 May 1995 10:27:04 GMT ETag: 7bc27-836-39a78e00 Accept-Ranges: bytes Content-Type: text/plain; charset=ISO-8859-1 Content-length: 2102 Connection: Keep-Alive Perhaps we are hitting different web servers? I ran nslookup on www.stats.ox.ac.uk, and it appears to be an alias for web2.stats.ox.ac.uk. Is that the machine you are getting? What happens if you run curl against web2, i.e.: curl --head http://web2.stats.ox.ac.uk/pub/datasets/csb/ch11b.dat ? (I get Content-length). Thanks, --Paul On 2/12/07, Charilaos Skiadas [EMAIL PROTECTED] wrote: On Feb 12, 2007, at 6:28 PM, Paul Lynch wrote: I'm trying to build R on RedHat EL4. The compile went fine, but a make check ran into a problem and produced a file internet.Rout.fail. Judging by the last part of that file, it was trying to run an R routine called httpget to retrieve the URL http://www.stats.ox.ac.uk/pub/datasets/csb/ch11b.dat. The precise error it encountered was: Error in strsplit(grep(Content-Length, b, value = TRUE), :)[[1]] : subscript out of bounds So, it looks like the data it read from that URL was not what was expected. I tried mimicking the script's request of the header information for that URL, and got back the following header lines: HTTP/1.1 200 OK Date: Mon, 12 Feb 2007 23:22:06 GMT Server: Apache/2.0.40 (Red Hat Linux) Last-Modified: Fri, 19 May 1995 10:27:04 GMT ETag: 7bc27-836-39a78e00 Accept-Ranges: bytes Content-Type: text/plain; charset=ISO-8859-1 Content-length: 2102 Connection: Keep-Alive The script appears to be looking for a Content-Length field, but as you can see the returned header is Content-length with a lower-case l. I don't know R yet, so I'm not sure if the grep in the test code is case-sensitive or not, but if it is, that would seem to be the problem. But then, surely everyone would be hitting this error? The grep is indeed case sensitive, as a quick test can show. However, the header I got back when I tried the above address had Length in it: HTTP/1.1 200 OK Date: Tue, 13 Feb 2007 01:40:48 GMT Server: Apache/2.0.40 (Red Hat Linux) Last-Modified: Fri, 19 May 1995 10:27:04 GMT ETag: 7bc27-836-39a78e00 Accept-Ranges: bytes Content-Length: 2102 Content-Type: text/plain; charset=ISO-8859-1 X-Pad: avoid browser bug ( I used curl for this, if it makes a difference) Hope this helps in some way. --Paul Haris __ 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] make check failure, internet.Rout.fail, Error in strsplit
I just happen to also have a MacOS 10.4 machine, but when I tried from there, I still got Content-length. Anyway, I am fairly certain that headers received from web servers would not be modified by the receiving machine or anything in-between. I suspect that the machine at www.stats.ox.ac.uk, even though we see it as the same IP, must be doing some sort of load balancing, probably on the basis of our IP addresses, and sending our requests to different servers. If this is correct, then it would seem that the test code for this part of the make test should be modified to do the grep in a case-insensitive way, or at the very least to support Content-length. I guess the next thing to do would be to submit a bug report. Thanks a lot for helping me look into this problem, --Paul On 2/13/07, Charilaos Skiadas [EMAIL PROTECTED] wrote: On Feb 13, 2007, at 11:16 AM, Paul Lynch wrote: Thanks for giving it a try. It is very odd that you got Content-Length when I am getting Content-length. I just tried curl (I had been using telnet to port 80) and I got the same (error causing) length result: Perhaps we are hitting different web servers? I ran nslookup on www.stats.ox.ac.uk, and it appears to be an alias for web2.stats.ox.ac.uk. Is that the machine you are getting? I get: Server: 192.200.129.190 Address:192.200.129.190#53 Non-authoritative answer: www.stats.ox.ac.uk canonical name = web2.stats.ox.ac.uk. Name: web2.stats.ox.ac.uk Address: 163.1.210.2 What happens if you run curl against web2, i.e.: curl --head http://web2.stats.ox.ac.uk/pub/datasets/csb/ch11b.dat ? (I get Content-length). I get Content-Length. I'm on MacOSX 10.4.8, don't know if that makes any difference. Thanks, --Paul Haris __ 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] make check failure, internet.Rout.fail, Error in strsplit
I'm trying to build R on RedHat EL4. The compile went fine, but a make check ran into a problem and produced a file internet.Rout.fail. Judging by the last part of that file, it was trying to run an R routine called httpget to retrieve the URL http://www.stats.ox.ac.uk/pub/datasets/csb/ch11b.dat. The precise error it encountered was: Error in strsplit(grep(Content-Length, b, value = TRUE), :)[[1]] : subscript out of bounds So, it looks like the data it read from that URL was not what was expected. I tried mimicking the script's request of the header information for that URL, and got back the following header lines: HTTP/1.1 200 OK Date: Mon, 12 Feb 2007 23:22:06 GMT Server: Apache/2.0.40 (Red Hat Linux) Last-Modified: Fri, 19 May 1995 10:27:04 GMT ETag: 7bc27-836-39a78e00 Accept-Ranges: bytes Content-Type: text/plain; charset=ISO-8859-1 Content-length: 2102 Connection: Keep-Alive The script appears to be looking for a Content-Length field, but as you can see the returned header is Content-length with a lower-case l. I don't know R yet, so I'm not sure if the grep in the test code is case-sensitive or not, but if it is, that would seem to be the problem. But then, surely everyone would be hitting this error? Can anyone offer some suggestions as how to proceed from here? Thanks, --Paul __ 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.
