Yes, I am a newbie at R, but it is not the complex commands in R that have me baffled, but simple data commands. For example, why does something like: > plot(Girth ~ Height) *not* work after a command that allegedly loads the data: > data(trees) with the error message: Error in eval(expr, envir, enclos) : Object "Girth" not found but does work after the command: > attach(trees) ? - JRV -- There are 10 kinds of people: those who understand binary, and those who don't
On Mon, 2004-11-08 at 21:56, Dr. John R. Vokey wrote:> Yes, I am a newbie at R, but it is not the complex commands in R that > have me baffled, but simple data commands. For example, why does > something like: > > > plot(Girth ~ Height) > > *not* work after a command that allegedly loads the data: > > > data(trees) > > with the error message: > > Error in eval(expr, envir, enclos) : Object "Girth" not found > > but does work after the command: > > > attach(trees) > > ?As per ?attach: "By attaching a data frame to the search path it is possible to refer to the variables in the data frame by their names alone, rather than as components of the data frame (eg in the example below, height rather than women$height)." data(trees) simply loads the dataset, but does not place it in the search path, which is what attach(trees) does. Prior to using attach(trees), you would need to use: plot(trees$Girth ~ trees$Height) to tell R that the variables Girth and Height are in the data frame called 'trees'. HTH, Marc Schwartz
It would work if you modified as follows: plot(lm(Girth~Height)) Or alternatively, fm1<-lm(Girth~Height);plot(fm1) Harold -----Original Message----- From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Dr. John R. Vokey Sent: Monday, November 08, 2004 10:56 PM To: r-help at stat.math.ethz.ch Subject: [R] no doubt a dumb question, but.. Yes, I am a newbie at R, but it is not the complex commands in R that have me baffled, but simple data commands. For example, why does something like: > plot(Girth ~ Height) *not* work after a command that allegedly loads the data: > data(trees) with the error message: Error in eval(expr, envir, enclos) : Object "Girth" not found but does work after the command: > attach(trees) ? - JRV -- There are 10 kinds of people: those who understand binary, and those who don't ______________________________________________ R-help at 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
On Monday 08 November 2004 19:56, Dr. John R. Vokey wrote:> Yes, I am a newbie at R, but it is not the complex commands in R that > have me baffled, but simple data commands. For example, why does > > something like: > > plot(Girth ~ Height) > > *not* work after a command that allegedly loads the data: > > data(trees) > > with the error message: > > Error in eval(expr, envir, enclos) : Object "Girth" not found > > but does work after the command: > > attach(trees) >I have wondered this myself, but one reason may be that more than one data table can be loaded at a time. Quite often data tables will use the same names for fields. It would inconvenient for instance, if you had two tables loaded, say one for trees and one for melons with a field named "Girth", and tried a plot(Girth ~ Height) command. So data() more or less accesses that table, and attach explicit identifies the table of interest. JWDougherty