On Thu, 1 Apr 2004, Anne Gosset wrote: > Hi, > > I am a brand new user of R and I have a really stupid problem: I am > having troubles applying fft on 2D matrices. I import a data file of > 256*256 elements with read.table (it is actually a grey scale image, the > corresponding data file being generated with Matlab), and I find that > the fft can be applied on one single column of data, but not on one row. > (Error message: Error in fft(z, inverse) : non-numeric argument ) > > Is it the format of the matrix which causes that trouble? (although I > checked with the editor that the matrix was well imported) Besides this, > it is not possible to plot one single row of data (strange plot with the > names of variables appearing). >
You probably have a data.frame rather than a matrix, as that is what read.table() produces. The difference is not obvious to the untrained eye, but a data.frame is a list of columns of potentially different types, so a single column reduces to a vector but a single row does not. Use as.matrix() on your data frame to convert it to a matrix. -thomas ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html