Reading data/variables
Well, if your problem is that a workspace is being loaded automatically and you don't want that workspace, you have several options: 1. Use a different directory for each project so that the file loaded by default is the correct one. 2. Don't save your workspace, but regenerate it each time. 3. Use R --vanilla or your OS's equivalent to start R without loading anything automatically, and use load() and save() to manually manage RData files. Yes, it's convenient, but if you want to use a non-standard way of working you need to understand what you're doing. Sarah
On Thu, Nov 17, 2011 at 3:10 AM, Steven Yen <syen at utk.edu> wrote:
Thanks Sarah. I have read about the problems with attach(), and I will try
to avoid it.
I have now found the line that's causing the problem is:
setwd("z:/homework")
With that line in place, either in a program or in Rprofile.site (?), then
the moment I run R and simply enter (before reading any data)
summary(mydata)
I get sample statistics for a dozen variables!
Do not save the workspace? I thought the option to save/use a binary file is
meant to be convenient.
I like working in the same working directory, and I like .rdata files. Does
this sound hopeless? Thanks.
At 09:26 PM 11/15/2011, Sarah Goslee wrote:
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 <syen at 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
? >