Hello,
I have a question on export and import data. Thank you for any suggestions.
data 'simul' is generated as follows:
N <- 20
n <- N/2
nsets <- 10
simul <- matrix(0,nsets,N)
th <- c(0,1, 1)
for(i in 1:nsets){
simul[i,] <- rnorm(N,mean= rep(th[1:2],N/2),sd=th[3])
}
I exported data as follows:
write.table(simul, file="D:\\test.txt", row.names=F, col.names=F)
When I want to use this data, I imported as follows:
a=read.table("D:\\test.txt")
So far, it works well. When I deal with data, I need use each row to do
calculations:
for(rep in 1:nsets){
y <- a[rep,]
b<-c(mean(y)+3, mean(y)-4) # cannot calculate mean(y), the mean of this row
m<-sd(y) # also cannot calculate sd(y)
}
I need a lot of calculation based on y, but after I imported data, R comes
error on it.
Could you please give me some suggestions?
--
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Exactly what errors are you getting? What is the 'str(a)' so we have an idea of the data you are processing. Why don't you use save/load so that the data is saved in the original format. Have you checked the structure of the data before/after the write.table/read.table? Also take a look at what is being returned with your 'mean(a[rep,])'; this would appear to be multivalued depending on what your dataframe is: e.g.,> x <- data.frame(a=1:10, b=1:10, c=letters[1:10]) > mean(x)a b c 5.5 5.5 NA Warning message: In mean.default(X[[3L]], ...) : argument is not numeric or logical: returning NA So there is more information that you have to provide; also try to look at the structure of all your objects to see if they are what you think they should be. On Wed, Dec 2, 2009 at 6:36 PM, aegea <gcheer3 at gmail.com> wrote:> > Hello, > > I have a question on export and import data. Thank you for any suggestions. > > data 'simul' is generated as follows: > N ? ? <- 20 > n ? ? <- N/2 > nsets <- 10 > simul <- matrix(0,nsets,N) > th ? ?<- c(0,1, 1) > for(i in 1:nsets){ > ? ?simul[i,] <- rnorm(N,mean= rep(th[1:2],N/2),sd=th[3]) > } > > I exported data as follows: > write.table(simul, file="D:\\test.txt", row.names=F, col.names=F) > > When I want to use this data, I imported as follows: > a=read.table("D:\\test.txt") > > So far, it works well. When I deal with data, I need use each row to do > calculations: > > for(rep in 1:nsets){ > y ? <- a[rep,] > b<-c(mean(y)+3, mean(y)-4) # cannot calculate mean(y), the mean of this row > m<-sd(y) ? # also cannot calculate sd(y) > } > > I need a lot of calculation based on y, but after I imported data, R comes > error on it. > > Could you please give me some suggestions? > > > -- > View this message in context: http://n4.nabble.com/calculation-problem-when-export-and-import-data-tp947250p947250.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at 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. >-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve?
After
a=read.table("test.txt")
do this:
a <- as.matrix(a)
read.table() gives you a data frame. You are assuming it is a matrix,
so change it into a matrix.
-Don
At 3:36 PM -0800 12/2/09, aegea wrote:>Hello,
>
>I have a question on export and import data. Thank you for any suggestions.
>
>data 'simul' is generated as follows:
>N <- 20
>n <- N/2
>nsets <- 10
>simul <- matrix(0,nsets,N)
>th <- c(0,1, 1)
>for(i in 1:nsets){
> simul[i,] <- rnorm(N,mean= rep(th[1:2],N/2),sd=th[3])
>}
>
>I exported data as follows:
>write.table(simul, file="D:\\test.txt", row.names=F, col.names=F)
>
>When I want to use this data, I imported as follows:
>a=read.table("D:\\test.txt")
>
>So far, it works well. When I deal with data, I need use each row to do
>calculations:
>
>for(rep in 1:nsets){
>y <- a[rep,]
>b<-c(mean(y)+3, mean(y)-4) # cannot calculate mean(y), the mean of this
row
>m<-sd(y) # also cannot calculate sd(y)
>}
>
>I need a lot of calculation based on y, but after I imported data, R comes
>error on it.
>
>Could you please give me some suggestions?
>
>
>--
>View this message in context:
>http://*n4.nabble.com/calculation-problem-when-export-and-import-data-tp947250p947250.html
>Sent from the R help mailing list archive at Nabble.com.
>
>______________________________________________
>R-help at 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.
--
---------------------------------
Don MacQueen
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062
macq at llnl.gov