[R] Read data from .csv file as a matrix

[Nordlund, Dan (DSHS/RDA)]

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of vincent.deluard
> Sent: Wednesday, May 05, 2010 12:34 PM
> To: r-help at r-project.org
> Subject: [R] Read data from .csv file as a matrix
> 
> 
> Hi R-users,
> 
> 
> I have a csv file that contains weather observation (rows) by days (in
> columns).
> 
> I open using:
> 
> > temp = read.csv("Weather.csv", sep=",")
> 
> and read:
> 
>              X X1.Jan X2.Jan X3.Jan X4.Jan
> 1          Min      2      3      4      1
> 2          Max      6     10      8      6
> 3 Forecast Min      3      1      1      3
> 4 Forecast Max      8      7      4      9
> 
> If I type
> 
> mean(temp[2,2:3])
> 
> I get
> 
> X1.Jan X2.Jan
>      6     10
> 
> The same command on
> 
> > y = matrix(1:21, ncol=7)
> 
> > mean(y[2,2:3])
> [1] 6.5
> 
> Works because the data is in a matrix. I believe R stores the data from
> the
> csv file as a data.frame with these annoying headers. So how do I
> convert
> the data from my csv file into a matrix?
> 
> I tried as.matrix but it did not help.
> 
> 
> Many many thanks!

I'm only guessing because you haven't given us much to go on, but maybe something like

mean(unlist(temp[2,2:3]))

Hope this is helpful,

Dan

Daniel J. Nordlund
Washington State Department of Social and Health Services
Planning, Performance, and Accountability
Research and Data Analysis Division
Olympia, WA 98504-5204