search for: expression

Something in new() or validObject() in the methods package is messing up. This happens in both 2.1.0 and R-devel in Windows. I'd like to have an empty expression for a slot in a class. An empty expression is an expression: > is.expression(expression()) [1] TRUE > > is(expression(), "expression") [1] TRUE > class(expression()) [1] "expression" However, when I try to use this as the initial value, I get an error thrown...

Dear all, I am confused about how to create an expression. I use a package (rsbml) which uses expressions and seems to make a difference if there is a quote around the expression or not. For example, package works with expressions such as > expression(A + B) but not with > expression("A + B") I now have a set of math expressions represe...

# The result I am after is the result after a substitution in an expression, such as substitute(expression(a+b+c), list(a=1)) expression(1 + b + c) # However, the way I want to do it is for a an expression "stored as a variable" as (expr <- expression(a+b+c)) expression(a + b + c) # a) The following does not work (expr2 <- substitute(expr, list(a=1)))...

Hi, I am not sure if this is a bug or a non-implement feature of text-drawing functions with TeX-style expression, but hat() and some of its equals does not get the right "bounding boxes" if they are put in sub- or superscripts. For instance, for the expression 'b[hat(a)]' the hat() seems to shift 'hat(a)' too much to the right of 'b'. Try the below example and you'll see...

Dear all, Suppose I have a very long expression e. Lets assume, for simplicity, that it is e = expression(u1+u2+u3) Now I wish to replace u2 with x and u3 with 1. I.e. the 'new' expression, after replacement, should be: > e expression(u1+x+1) My question is how to do the replacement? I have tried using: > e = parse(text=gsub(...

Greetings, I have a problem that I am sure is very straightforward, but I just can't wrap my head around it. I've read the help pages on text, plotmath, expression, substitute, but somehow I can't find the answer to this simple question. Basically consider the following example: plot( NULL, xlim = c(0,2), ylim = c(0,2) ) expressions <- expression( -infinity, infinity ) text( c(0.5,1.5), 1.5, expressions ) labels <- c( "-infinity", &qu...

Hallo I'm having trouble figuring out how to evaluate an expression when one of the variables in the expression is defined separately as a sub expression. Here's a simplified example mat <- expression(0, f1*s1*g1) # vector of formulae g1 <- expression(1/Tm) # expansion of the definition of g1 vals <- data.frame(f1=1, s1=.5, Tm=2) # one set o...

On Aug 22, 2013, at 6:42 PM, Shankar Easwaran <shankare at codeaurora.org> wrote: > On 8/22/2013 3:44 PM, Nick Kledzik wrote: >> >> Linker scripts have the same need. My idea for this was to allow atoms to have an associated expression tree and would have references to all symbols in that tree. The resolver wouldn't need any special handling for this, and the backend would just need to evaluate the expression at the end. >> Agreed. >> >> On one hand, this sounds like an AbsoluteAtom because it has no conten...

Hi all Can anybody help me with this? I am trying to include in an automatic way the argument in arg.names in a barplot. I generate the labels I want to appear below the bars with a for loop, and they contain subscripts, so I need to use expression anch<-0.05 esp<-4 for (i in 1:dim(Ntot)[1]) { naux<-Ntot[i,] naux2<-naux[naux>0] nind<-which(naux>0) tit4<-character(0) for (j in 1:length(nind)) { tit4<-c(tit4,paste("expression(n[paste[",i,",",nind[j],"...

I am sure it is just me not understanding how R works, but could somebody explain why curve(cos(x)) works and curve(expression(cos(x)) does not? I have done some investigating and here is what I found. If I comment out the line of curve indicated below, both calls work fine. function (expr, from, to, n = 101, add = FALSE, type = "l", ylab = NULL, log = NULL, xlim = NULL, ...) { sexpr <- substitute(...

...rform symbolic derivation. This works very well and it is much faster than e.g. Mathematica (at least for my purposes). First, I would like to thank the development team for this excellent function. However, I run into trouble in some cases, particularly when I am to do some operations on long expressions obtained from using D. The problem seems to occur when I convert a 'call' or an 'expression' to a 'character', then some parts of the original 'expression' is lost. Is there some way of transforming a call or an expression into a character string that I do not kno...

When investigating the legend(x,y, expression ( <math>, <math> ), ....) [as suggested by Jim Lindsey], I once again stumbled over the fact that expression objects behave somewhat ``wierdly'', IMHO. We can have expressions of length(.) > 1, and access elements of these like list elements. However, other natural thing...

I have been struggling with this problem for a while and I hope someone could help me. Or if someone could point me to a section in the manual I would be grateful. x <- "my" plot(1:10, main=expression(paste( x, Delta, "values" ))) Q : How do I get the title to say "my (triangle symbol) values" ? The following trial-and-error produced mainly errors : plot(1:10, main=expression(paste( get(x), Delta, "values" ))) plot(1:10, main=expression(paste( substitute(x),...

On Aug 22, 2013, at 1:32 PM, Michael Spencer <bigcheesegs at gmail.com> wrote: > On Thu, Aug 22, 2013 at 12:54 PM, Shankar Easwaran <shankare at codeaurora.org> wrote: > Hi Nick, > > I am planning to work on adding support for definining expressions for the Gnu flavor. > > Currently Gnu ld supports an option --defsym symbol=expression. The expression may be composed of other symbols. > Any symbol that appears in the expression, gets its value from the output symbol value (address of the symbol in the output file). > > In addi...

Hi, I am trying to implement Available Expressions data flow analysis. I created the following class (I am giving here code snippet.): namespace { typedef DenseMap<Expression, uint32_t> DMTy; //Expression is a class I defined. struct DataFlowValue { DMTy ExprMap; llvm::BitVector* DFV; // Functions operating on the data //...

Recent questions about using plotmath have renewed my interest in this question I want to have expressions take values of variables from the environment. I am able to use expressions, and I am able to use paste to put text and values of variables into plots. But the two things just won't work together. Here is some example code that shows what I mean. plot(NA,xlim=c(0,100),ylim=c(0,100)) #show...

Hi everyone, I am hoping someone can help with my attempted use of the expression function. I have a long series of text and variable to paste together including a degree symbol. The text is to be placed on my scatter plot using the mtext function. Using expression like this: changetext = expression(paste("Change from ",mini," to ", maxi, ":", dif...

Hi, I am writing a function and need to pass a function expression as an argument, for instance, myfun <- function( express) { x<- c(1,2,3) y<-express } if I call the above function by myfun( x*2 ), I get 2 as the result, instead of 2,4,6 , could someone help me to fix this problem ?...

I am using expressions to annotate x and y labels in plots. I start of with a label as xlab <- expression(X) Note that it is the user that sets this. It could also be something more complicated as expression(sqrt(R*G)). Can I easily add a log[2] "around" this expression? I would like to get xlab <...

...at codeaurora.org>wrote: > Hi Nick, > > Thanks for your reply. > > > On 8/23/2013 3:40 PM, Nick Kledzik wrote: > >> >> These are the changes I plan to make, and some questions that I have >> >> a) Define a new contentType for DefinedAtoms to say 'Expression' >> b) Create a new class ExprnAtom derived from DefinedAtom >> c) The expression could also contain various functions that could be set >> in the expression, how should that be represented ? >> I don’t understand this. I thought expression where like "_foo + 10”....