Hi, The obvious answer is don't use attach() and you'll never have that problem. And see further comments inline.
On Tue, Nov 15, 2011 at 6:05 PM, Steven Yen <s...@utk.edu> wrote: > Can someone help me with this variable/data reading issue? > I read a csv file and transform/create an additional variable (called y). > > The first set of commands below produced different sample statistics > for hw11$y and y > > In the second set of command I renameuse the variable name yy, and > sample statistics for $hw11$yy and yy are identical. > > Using y <- yy fixed it, but I am not sure why I would need to do that. > > That "y" appeared to have come from a variable called "y" from > another data frame (unrelated to the current run). > > Help! > > > setwd("z:/homework") > > sink ("z:/homework/hw11.our", append=T, split=T) > > hw11 <- read.csv("ij10b.csv",header=T) > > hw11$y <- hw11$e3 > > attach(hw11) > The following object(s) are masked _by_ '.GlobalEnv': > y Look there. R even *told* you that it was going to use the y in the global environment rather than the one you were trying to attach. The other solution: don't save your workspace. Your other email on this topic suggested to me that there is a .RData file in your preferred working directory that contains an object y, and that's what is interfering with what you think should happen. Deleting that file, or using a different directory, or removing y before you attach the data frame would all work. But truly, the best possible strategy is to avoid using attach() so you don't have to worry about which object named y is really being used because you specify it explicitly. > > (n <- dim(hw11)[1]) > [1] 13765 > > summary(hw11$y) > Min. 1st Qu. Median Mean 3rd Qu. Max. > 0.0000 0.4500 1.0000 1.6726 2.0000 140.0000 > > length(hw11$y) > [1] 13765 > > summary(y) > Min. 1st Qu. Median Mean 3rd Qu. Max. > 0.00000 0.00000 0.00000 0.24958 0.00000 1.00000 > > length(y) > [1] 601 > > > > > setwd("z:/homework") > > sink ("z:/homework/hw11.our", append=T, split=T) > > hw11 <- read.csv("ij10b.csv",header=T) > > hw11$yy <- hw11$e3 > > attach(hw11) > > hw11$yy <- hw11$e3 > > summary(hw11$yy) > Min. 1st Qu. Median Mean 3rd Qu. Max. > 0.0000 0.4500 1.0000 1.6726 2.0000 140.0000 > > length(hw11$yy) > [1] 13765 > > summary(yy) > Min. 1st Qu. Median Mean 3rd Qu. Max. > 0.0000 0.4500 1.0000 1.6726 2.0000 140.0000 > > length(yy) > [1] 13765 > > > -- Sarah Goslee http://www.functionaldiversity.org ______________________________________________ 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.