On 3/2/07, Marc Schwartz <[EMAIL PROTECTED]> wrote: > On Fri, 2007-03-02 at 08:53 -0600, hadley wickham wrote: > > > 3. Depending on the nature of your data, if the extreme value is > > > representative of an important marked difference relative to the other > > > values, then I don't particularly find the 'look' of the plot to be > > > overly problematic. It does appropriately emphasize the large > > > difference. > > > > > > On the other hand, you might want to consider using a log scale on the y > > > axis as an alternative to an axis gap. This would be a reasonable > > > approach to plotting values that have a notable difference in range. If > > > you do this, note that you would need to ensure that all y values are >0 > > > (ie. y axis range minimum, lower bounds of CI's, etc.) since: > > > > > > > log10(0) > > > [1] -Inf > > > > > > > > > > Of course, you can't do this with a bar plot, because bars should be > > anchored at 0. > > Both barplot() and barplot2() support log scaling for both x and y axes. > > In both functions, the default axis minimum for the 'height' axis (y by > default, x if 'horizontal = TRUE') will be 0.9 * min(height) to avert > log10(0) related issues. Errors will be issued otherwise if any values > of 'height' are <= 0 or 'ylim'/'xlim' args are similarly set.
I think that's a pretty bad idea - in a bar plot you are comparing the ratio of heights of the bars, not the absolute heights. It's the same reason it's a bad idea to have a bar graph with a non-0 y-axis - it's misleading. Hadley ______________________________________________ [email protected] 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.
