[R] Getting lm() to work with a matrix
Hi I'm fairly new to R and am trying to analyse some large spectral datasets using stepwise regression (fairly standard in this area). I have a field sampled dataset, of which a proportion has been held back for validation. I gather than step() needs to be fed a regression model and lm() can produce a multiple regression. I had thought something like: spectra.lm - lm(response[,3]~spectra.spec[,2:20]) might work but lm() doesnt appear to like being fed a range of columns. I suspect Ive missed something fairly fundamental here. Any help much appreciated best wishes mike -- View this message in context: http://www.nabble.com/Getting-lm%28%29-to-work-with-a-matrix-tp23625486p23625486.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
[R] Row number of minimum value?
Hi This *must* be an insanely easy thing to work out, but I'm not too familiar with R syntax. So how do I work out the row number (if I pass a column) of the minimum value?? I can get the value itself from min(), but where can I get the row?? Many thanks mike -- View this message in context: http://www.nabble.com/Row-number-of-minimum-value--tp23578215p23578215.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
Re: [R] Using column length in plot gives error
Hi Stephanie Absolutely right! My CSV was imported as a factor. Reading the R FAQ: http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-do-I-convert-factors-to-numeric_003f I actually need to do: as.numeric(as.character(spectra.wavelength)) to get back to my original data. Many thanks for the pointer mike Stephanie Kovalchik wrote: Is spectra.wavelength a factor? If so, plot will treat it as categorical and not draw a line. Try the following modification. plot(as.numeric(spectra.wavelength), cormat, type = l, ylim=c(-1,1), xlab=Wavelength (nm), ylab=Correlation) Quoting MikSmith m...@hsm.org.uk: Hi I'm trying to write a generic script for processing some data which finishes off with some plots. Given Im never sure how many columns will be in my dataframe I wanted to using the following plot(spectra.wavelength, cormat, type = l, ylim=c(-1,1), xlab=Wavelength (nm), ylab=Correlation) however even if I specify as type=l it appears plot as points (right hand plot). If I specify a range such as plot(650:700, cormat, type = l, ylim=c(-1,1), xlab=Wavelength (nm), ylab=Correlation) it looks good (left hand plot). If I try something like: plot(spectra.wavelength[1]:spectra.wavelength[length(spectra.wavelength)], cormat, type = l, ylim=c(-1,1), xlab=Wavelength (nm), ylab=Correlation) it fails with variable lengths differ and when I look at spectra.wavelength[1] it gives me the value but then states there are 53 levels. What does this mean and how can I get the result I want??! many thanks mike http://www.nabble.com/file/p23562717/1.pdf 1.pdf -- View this message in context: http://www.nabble.com/Using-column-length-in-plot-gives-error-tp23562717p23562717.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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. __ R-help@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. -- View this message in context: http://www.nabble.com/Using-column-length-in-plot-gives-error-tp23562717p23582038.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
Re: [R] Row number of minimum value?
Hi Adrian Many thanks. That works perfectly! It's easy when you know the answer :) mike Adrian Dusa wrote: Hi Mike, On Sunday 17 May 2009, MikSmith wrote: Hi This *must* be an insanely easy thing to work out, but I'm not too familiar with R syntax. So how do I work out the row number (if I pass a column) of the minimum value?? I can get the value itself from min(), but where can I get the row?? Maybe this helps: which(mycol == min(mycol)) where mycol is your column. Hth, Adrian -- Adrian Dusa Romanian Social Data Archive 1, Schitu Magureanu Bd. 050025 Bucharest sector 5 Romania Tel.:+40 21 3126618 \ +40 21 3120210 / int.101 Fax: +40 21 3158391 __ R-help@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. -- View this message in context: http://www.nabble.com/Row-number-of-minimum-value--tp23578215p23582001.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
[R] Using column length in plot gives error
Hi I'm trying to write a generic script for processing some data which finishes off with some plots. Given Im never sure how many columns will be in my dataframe I wanted to using the following plot(spectra.wavelength, cormat, type = l, ylim=c(-1,1), xlab=Wavelength (nm), ylab=Correlation) however even if I specify as type=l it appears plot as points (right hand plot). If I specify a range such as plot(650:700, cormat, type = l, ylim=c(-1,1), xlab=Wavelength (nm), ylab=Correlation) it looks good (left hand plot). If I try something like: plot(spectra.wavelength[1]:spectra.wavelength[length(spectra.wavelength)], cormat, type = l, ylim=c(-1,1), xlab=Wavelength (nm), ylab=Correlation) it fails with variable lengths differ and when I look at spectra.wavelength[1] it gives me the value but then states there are 53 levels. What does this mean and how can I get the result I want??! many thanks mike -- View this message in context: http://www.nabble.com/Using-column-length-in-plot-gives-error-tp23562704p23562704.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
[R] Using column length in plot gives error
Hi I'm trying to write a generic script for processing some data which finishes off with some plots. Given Im never sure how many columns will be in my dataframe I wanted to using the following plot(spectra.wavelength, cormat, type = l, ylim=c(-1,1), xlab=Wavelength (nm), ylab=Correlation) however even if I specify as type=l it appears plot as points (right hand plot). If I specify a range such as plot(650:700, cormat, type = l, ylim=c(-1,1), xlab=Wavelength (nm), ylab=Correlation) it looks good (left hand plot). If I try something like: plot(spectra.wavelength[1]:spectra.wavelength[length(spectra.wavelength)], cormat, type = l, ylim=c(-1,1), xlab=Wavelength (nm), ylab=Correlation) it fails with variable lengths differ and when I look at spectra.wavelength[1] it gives me the value but then states there are 53 levels. What does this mean and how can I get the result I want??! many thanks mike http://www.nabble.com/file/p23562717/1.pdf 1.pdf -- View this message in context: http://www.nabble.com/Using-column-length-in-plot-gives-error-tp23562717p23562717.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
[R] rbind help
Hi I have a dataset of orientation and elevation in a dataframe which I am plotting in circular. Orientation is on the range 0-360, however I need to reduce this to 0-180 as the values over 180 are not necessarily correct. I can do striae$orientation[striae$orientation180]-180) to extract these values, but I then want to combine them back in to the original dataframe (with the elevation values). I assume rbind is the thing to use and have tried something like: test - rbind((striae$orientation[striae$orientation180]-180), (striae$orientation[striae$orientation=180])) Not being a regular R user I suspect the syntax is easy when you know it!! Any help much appreciated. Best wishes mike -- View this message in context: http://www.nabble.com/rbind-help-tp23499705p23499705.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
[R] Graphic aspect ratio
Hi I've been playing with a 3x2 graphics device using the default size as it appears on screen. This has given me tall thin plots which I can resize by dragging the window and increasing the window width. However I was wondering if I can force R to produce square plots or set the actual aspect ratio. asp seems to affect data units, not on-screen pixel units. thanks mike -- View this message in context: http://www.nabble.com/Graphic-aspect-ratio-tp23503495p23503495.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
[R] Add data count to plot?
Hi I'm a relative newbie to R and had a query concerning plotting. I have generated a par(mfrow = c(2, 2)) graphic with 10 rose diagrams using circular. What I wanted to add to each individual plot was n = x for the number of data observations in each dataset. How might I go about doing this?? Thanks Mike -- View this message in context: http://www.nabble.com/Add-data-count-to-plot--tp23491681p23491681.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
