[R] calculation problem when export and import data

jim holtman jholtman at gmail.com
Thu Dec 3 04:04:19 CET 2009

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.
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Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

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