[R] RNORM matrix based on CSV file values for MEAN and SD

[R. Michael Weylandt]

On Tue, May 22, 2012 at 12:40 PM, dcoakley <danielcoakley1 at gmail.com> wrote:
> Thanks Michael,
>
> This seems to get me half-way towards a solution. However, I am still having
> some difficulty in getting the out.csv exactly as I would like. I should
> probably explain the issue a bit further.
>
> I am reading in a csv file containing a list of 'n' parameters. I have
> attached a csv ( http://r.789695.n4.nabble.com/file/n4630928/read.csv
> read.csv ) which contains 10 parameters as an example. However, the final
> problem may have up to 2000 parameters. Currently, these have string titles
> in the first column. However, I can change these to numbers if it causes
> problems in R.

It looks like

read.csv("http://r.789695.n4.nabble.com/file/n4630928/read.csv")

works just fine for me here -- can you provide the code you're using
to read things in? It might be that you need header = TRUE if you're
using read.table() instead of read.csv() [The only reason I'm having
you use write.table() is that write.csv() doesn't append nicely]

>
> As you said correctly, this will give me a data.frame with mean and sd
> values.
>
> The problem I have is in the creation of the matrix of rnorm values. Using
> the for loop specified, I am getting a single column with the rnorm values
> for the last parameter specified (see attached
> http://r.789695.n4.nabble.com/file/n4630928/out.csv out.csv ). Re-running
> the for loop appends another column to the csv file, below the original
> column.

Ahh, my apologies -- you probably need to transpose your data to a row
before writing:

e.g.,

write.table(1:10, "temp.csv", sep = ",", row.names = FALSE, col.names = FALSE)
read.csv("temp.csv", header = FALSE)
# Gives a single column

write.table(t(1:10), "temp.csv", sep = ",", row.names = FALSE,
col.names = FALSE)
read.csv("temp.csv", header = FALSE)
# Gives a single row

Best,
Michael


>
> I have attached an example of the output I am looking for (
> http://r.789695.n4.nabble.com/file/n4630928/OutputSample.csv
> OutputSample.csv ). I believe, the approach here is correct, I just need to
> make a few modifications to the for loop. This also needs to be scalable to
> allow for the inclusion of multiple paramters (up to 2000) and samples (up
> to 1 million). I will look into the dataConnections process you mentioned to
> address this task.
>
> Also, just in case the above attachments don't work, here is a link to the
> shared files on Google Drive:
> https://docs.google.com/open?id=0Bwwrh1DeZXteSFBXNVI1NGZfQjg
>
> Thanks again for the help. Very much appreciated.
>
> --
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>
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