I am trying to get the following line in a plot margin using mtext: 100% Area = 120.000 km^2 Where I intend that "100% Area =" is text, 120.000 is a number that varies according to different data, and km^2 should be a neat km-with-superscript-2. The expression function fails me, since it apparently cannot coerce an expression when a variable is involved. In the R help file there is an example using either bquote or substitute to accomplish like things, but these are sufficiently different from my objective and I am becoming more and more confused by every further example I stumble on. This should be easy. Can anyone help me prevent spending anoter 2.5 hours on the matter? Thanks. -- View this message in context: http://www.nabble.com/Combining-math-and-variables-in-expression-tp22455877p22455877.html Sent from the R help mailing list archive at Nabble.com.
> tmp <- '120.000' > mtext(bquote( '100% Area' == .(tmp)~km^2 ))Hope this helps, -- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.snow at imail.org 801.408.8111> -----Original Message----- > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r- > project.org] On Behalf Of socrates > Sent: Wednesday, March 11, 2009 8:08 AM > To: r-help at r-project.org > Subject: [R] Combining math and variables in expression > > > I am trying to get the following line in a plot margin using mtext: > > 100% Area = 120.000 km^2 > > Where I intend that "100% Area =" is text, 120.000 is a number that > varies > according to different data, and km^2 should be a neat > km-with-superscript-2. > The expression function fails me, since it apparently cannot coerce an > expression when a variable is involved. > In the R help file there is an example using either bquote or > substitute to > accomplish like things, but these are sufficiently different from my > objective and I am becoming more and more confused by every further > example > I stumble on. > This should be easy. Can anyone help me prevent spending anoter 2.5 > hours on > the matter? Thanks. > -- > View this message in context: http://www.nabble.com/Combining-math-and- > variables-in-expression-tp22455877p22455877.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at 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.
Dear socrates; It did not take me 2.5 hours but it did take longer than I thought it would. I worked off the example given by Henrique Dallazuanna seen at: http://finzi.psych.upenn.edu/R/Rhelp08/archive/120065.html This seems "to work": mtext(bquote(100~"%" ~ Area == ~ .(text.val)~ Km^2), side=3) I cannot say the the syntactic rules are entirely clear. The proper placement of the tildes is a bit mysterious to me. I am wondering if a solution using substitute(expression(.)) might be more clear but my efforts in that direction were not successful. -- David On Mar 11, 2009, at 10:08 AM, socrates wrote:> > I am trying to get the following line in a plot margin using mtext: > > 100% Area = 120.000 km^2 > > Where I intend that "100% Area =" is text, 120.000 is a number that > varies > according to different data, and km^2 should be a neat > km-with-superscript-2. > The expression function fails me, since it apparently cannot coerce an > expression when a variable is involved. > In the R help file there is an example using either bquote or > substitute to > accomplish like things, but these are sufficiently different from my > objective and I am becoming more and more confused by every further > example > I stumble on. > This should be easy. Can anyone help me prevent spending anoter 2.5 > hours on > the matter? Thanks. > -- > View this message in context: http://www.nabble.com/Combining-math-and-variables-in-expression-tp22455877p22455877.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at 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.David Winsemius, MD Heritage Laboratories West Hartford, CT