> hadley wickham wrote: > > I'd do this a little differently, using the reshape > > (http://had.co.nz/reshape) and ggplot2 (http://had.co.nz/ggplot2) > > packages: > > > > library(reshape) > > library(ggplot2) > > > > # Get data in format required for reshape > > df <- rename(df, c("OD" = "value")) > > > > # Summarise and compute errors > > se <- function(x) sd(x)/sqrt(length(x)) > > means <- cast(df, Mutant + Time ~ ., c(mean, se)) > > > > qplot(Time, mean, data=means, colour=Mutant, min = mean - se, max = > > mean + se, geom=c("point","errorbar")) > > > > > > I can certainly see the value of a more elegant/automated/higher-level > solution > (although knowing the base-graphics way of going about it can be helpful > too). > > However, at least the first plot you suggest looks a little bit funny > to me. > Suppose that the x coordinates of the error > bar are x_L (left edge of bars), x_0 (middle of bars/location > of data point), and x_R (right edge of bars), and the y coordinates > are y_B, y_0, and y_U (bottom [min], middle, and top [max]). > The "errorbar" specification seems to add a series of > segments from (x_L,y_B) of one point to > (x_L,y_U) of the next [sorry if this is confusing, but I'm trying > to describe a picture ...] > > (1) this seems like a funny default (I wouldn't normally want this line > drawn if I specified "errorbars"), (2) even if one has the line, > the x-positions of the segment endpoints still seem wrong (or at least > a wrong default) -- I still > think they should line up with the x-coordinates of the data > > Poking around http://had.co.nz/ggplot2/geom_errorbar.html hasn't > resolved this (yet). > > I thought that breaking it down a bit might help, but it appears to do > the same thing ... > > p = ggplot(means, aes(x=Time, y=mean, > colour=Mutant,min=mean-se,max=mean+se)) > p + geom_errorbar() > > Can you see what I mean, or am I confused/have an old version/etc. ? >
Oooooh - oops. I completely forgot about that error - it's fixed in the current development version of ggplot which I should probably think about uploading to CRAN. > PS if one specifies "errorbars" without specifying min and max one gets > the error > > Error in rbind(max, max, max, min, min, min) : > cannot coerce type closure to list vector > > perhaps a more transparent error message could be supplied in this > (admittedly > stupid-user-error-obvious-in-hindsight) case? Yes, that's a good idea. I'm still working on making the error messages more user friendly. I think I'm making some progress, but it's fairly slow. Hadley -- http://had.co.nz/ ______________________________________________ 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.
