On Fri, 2003-11-07 at 14:29, Siddique, Amer wrote: > Should I be able to use axis() on a barplot? i have a data.frame, the first > 3 values of which are: > > > c[1:3,] > median mean > A1 56.5 58.50000 > A61 73.0 73.00000 > A62 63.0 63.00000 > > > str(c) > `data.frame': 19 obs. of 2 variables: > $ median: num 56.5 73 63 161 51 55 44.5 22 54 49 ... > $ mean : num 58.5 73.0 63.0 161.0 47.5 ... > > if I do barplot(median) and then try to label the bars with axis(), I get; > > > axis(1,,labels=rownames(c),font=4,cex=1) ^^ You have an error in your call to axis().
You are missing the 'at' argument. As a result, the default values of 'at' are set to axTicks(1), which in this case is returning 5 values. You have passed 19 values to the 'labels' argument in axis(). Hence the error message below. > Error in axis(side, at, labels, tick, line, pos, outer, font, vfont, lty, : > > location and label lengths differ, 5 != 19 > > even though > > barplot(median, names.arg=rownames(c)) works and > > > length(rownames(c)) > [1] 19 In the above call to barplot(), you have specified the bar names, which will be matched within the function to the number of bars, thus it works. > also when I attempt to place the value of the observation > above the bar it does not space properly across all bars: > > text(median,labels=median,pos=3,cex=0.6) > > do i need to explicitly state an x-pos for the co-ord argument here? Yes. You get the proper x axis values by calling barplot() in the following fashion: mp <- barplot(....) In this case, barplot() returns the bar midpoints and assigns them to 'mp'. Once you have that information, you can call text() with the x values set to 'mp'. See ?barplot for examples and you may wish to review the most recent R News, where there is an article on R's base graphics in R Help Desk. http://cran.r-project.org/doc/Rnews/Rnews_2003-2.pdf Just beware though....the author of that article has been known indulge in single malt scotches on Friday afternoons... ;-) HTH, Marc Schwartz ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help