search for: expressions

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"

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 represented as strings, something like this: > rhs_e...

# 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))) expr # b) - whereas this

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

...do the replacement? I have tried using: > e = parse(text=gsub("u2","x",e)) > e = parse(text=gsub("u3",1,e)) Even though this works fine in this simple example, the use of parse when e is very long will fail since parse has a maximum line length and will cut my expressions. I need to keep mode(e)=expression since I will use e further in symbolic derivation and division. Any suggestions are most welcome. Thank you. Regards, Daniel Berg

...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", "infinity" ) text( c(0.5,1.5), 0.5, as.expression(labels) ) I want the character vector "labels" to be interpreted as an expression vector, and so to appear j...

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 of possible values for

...he expression, that can be used to emit YAML information Or a parse tree of the expression. > e)The expression tree needs to be stored into the Native intermediate representation too right ? Store them as atoms ? How to represent constants and functions ? Well, technically the only places these expressions come from is the command line or linker scripts, so we don’t *have* to have a way to externalize the atoms in yaml or native format. But, it would be nice to allow that, so that some future C or asm extension would let you create these. > f) What about lld core ? > g) Create a new reference...

...hole expression as > tit5 [1] "c(expression(n[paste[5,1]),expression(n[paste[5,2]),expression(n[paste[5,3]),expression(n[paste[5,4]))" but it doesn't work neither I wonder if there is some way that barplot "tells" arg.names to "evaluate" the contents of tit4 as expressions, not as characters I hope I made myself clear enough Thanks in advance to any response Cheers!!!! Javi -- View this message in context: http://www.nabble.com/How-to-pass-a-character-argument-which-contains-expressions-to-arg.names-in-barplot--tp24630656p24630656.html Sent from the R help maili...

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 =

...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 know...

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 things don't work with expressions; some example code: ##-- `Simple' length--1 expressions: ex1 <- expression(hat(beta) == (X^t * X)^{-1} * X^t * y) ex2 <- expression(bar(x) == sum(over(x[...

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 :

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 addit...

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...

Reading the body of function 'AnswerType' in bind.c, called from 'do_c' and 'do_unlist', I notice that EXPRSXP and VECSXP are handled identically in the recurse = TRUE case. A corollary is that c(recursive = TRUE) and unlist(recursive = TRUE) treat expression vectors like expression(a, b) as lists of symbols and calls. And since they treat symbols and calls as

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, ":", diff

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 ? Furthermore, is that

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 <-...