[S] Follow up to Creating a dot plot with ordered values

["Steven P. Millard" <steven.p.millard@cwix.com>]

Hello,

Thanks to Frank Harrell and Naomi Robbins for letting me know about 
reorder.factor().  Using this function simplifies the command somewhat. 
 Instead of using the command

     dotplot(ordered(Y.labels, levels = Y.labels[order(Var)]) ~ Var,
          data = dum.df)

you can use the command

     dotplot(reorder.factor(Y.labels, Var) ~ Var, data = dum.df)

(Of course I'm assuming the variables Y.labels and Var are directly 
accessible.  If they are not, then you'd have to type dum.df$Y.labels 
and dum.df$Var.)

It looks to me like you have to use reorder.factor() from the command 
line; I don't think it is available in the menu.  In fact, I don't see 
anything on the menu to even let you set up ordered factors.


Sincerely,

--Steve M.

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***********Original Query*************************************

Hello,

I am using S-PLUS 4.5, Release 2.

On p. 152 of "The Elements of Graphing Data" by William S. Cleveland is 
the statement, "Typically, our perception of the distribution of the 
values on a dot plot is enhanced by graphing the data ordered from 
smallest to largest...One exception is the case in which the labels 
have an order...."

Wishing to follow this advice, I have found it somewhat easy to do with 
dotchart (an older S-PLUS function that is not a trellis function), but 
not as easy to do with dotplot or the menu selection (in fact I think 
there is a bug in the menu version).  I list an example below.

I find it a bit amusing that there is no argument to dotchart or 
dotplot that allows the user to specify ordering.  Does anyone know of 
a simpler way other than what I am doing to produce the same thing?

Thanks for your time!


As an example, create some variables and a data frame:

     Var <- c(1,2,4,3)
     Y.labels <- letters[1:4]
     dum.df <- data.frame(Var = Var, Y.labels = Y.labels)


If we use the dotchart function with defaults:

     dotchart(Var, Y.labels)

then the values are not ordered from smallest to largest, but this is 
relatively easy to fix with the following modified command:

> dotchart(rev(sort(Var)), rev(Y.labels[order(Var)]))


If we use the dotplot function with defaults:

     dotplot(Y.labels ~ Var, data = dum.df)

then again the values are not ordered from smallest to largest.  To fix 
this, you can use the following modified command:

     dotplot(ordered(Y.labels, levels = Y.labels[order(Var)]) ~ Var,
             data = dum.df)

If we use the 2D Graph menu and choose Dotplot, then set Data Set to 
dum.df, X Column(s) to Var, Y Column(s) to Y.labels, click on the 
Smooth/Sort tab, and set Pre-Sort Data to XY on X, the plot does not 
come out correctly.

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