On Aug 25, 2010, at 4:32 AM, e-letter wrote:
On 24/08/2010, David Winsemius <[email protected]> wrote:
On Aug 24, 2010, at 9:37 AM, e-letter wrote:
Readers,
According to the documentation for the function 'plotmath' there
is no
apparent possibility to add the percent sign (%) to a plot function,
Where did you see an assertion made???
Within R I entered the command:
?plotmath
Also accessed using:
help.start(browser="opera")
Navigating the web browser page:
packages
packages in /usr/lib/R/library
grdevices
plotmath
In the list headed 'syntax' and 'meaning' within the section
'details'.
e.g.
plot(a[,1]~b[,2],ylab=expression(x~%),xlab=expression(z))
How to achieve this please?
Read the plotmath helo page more carefully. The section immediatedly
below the plotmath expressions points you to the use of the symbol()
expression-function and to the points help page where generation of
the available glyphs proceeds according to the advice on
help(plotmath):
In my system the paragraph immediately after the list of features
(i.e. 'syntax','meaning') describes a note to TeX users. I cannot see
reference to 'symbol()'.
It's possible that my help page is different than yours. Right after
the syntax/meaning description on mine (which is a Mac OSX system) is
a paragraph:
"The symbol font uses Adobe Symbol encoding so, for example, a lower
case mu can be obtained either by the special symbol mu or by
symbol("m"). This provides access to symbols that have no special
symbol name, for example, the universal, or forall, symbol is
symbol("\042"). To see what symbols are available in this way
useTestChars(font=5) as given in the examples for points: some are
only available on some devices."
(In this case I would be surprised if the help pages were different
because this makes a cross-reference to the examples in points. I am
not surprised about cross-platform differences in descriptions of
graphical devices and would have included a caveat if I were
corresponding on rhelp about such. I suppose the font issues could be
platform specific so if you want to correct me on this point, I will
try to file it away. I did, however, give you the code needed to to
display Symbols and it sounds further on that it succeeded)
TestChars <- function(sign=1, font=1, ...)
+ {
+ if(font == 5) { sign <- 1; r <- c(32:126, 160:254)
+ } else if (l10n_info()$MBCS) r <- 32:126 else r <- 32:255
+ if (sign == -1) r <- c(32:126, 160:255)
+ par(pty="s")
+ plot(c(-1,16), c(-1,16), type="n", xlab="", ylab="",
+ xaxs="i", yaxs="i")
+ grid(17, 17, lty=1)
+ for(i in r) try(points(i%%16, i%/%16, pch=sign*i,
font=font,...))
+ }
TestChars(font=5)
Notice that the "%" sign is three characters to the right (i.e.
higher) of the "forall" symbol that is produced by the example code
I can't see 'forall' in the code above.
Gavin has already explained why you did not. The upside-down A (==
"universal" or "forall") was a useful reference point in the indexing,
since it is only 3 glyphs away for the "%" symbol.
they offer. (The numbering proceeds from bottom up which confused me
at first.)
What numbering?
Actually I did not see any numbering either, which was why I remained
confused about the location of the "%" symbol for several minutes.
Perhaps I should have used the term "indexing".
The documentation makes reference to the command:
demo(plotmath)
I applied this command and could not see an instruction to produce the
percent (%) symbol.
I don't think I suggested it would.
--
David Winsemius, MD
West Hartford, CT
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