Displaying 20 results from an estimated 1000 matches similar to: "Puzzled at ifelse()"
2009 Dec 09
4
equivalent of ifelse
Hi,
Is there any equivalent for ifelse (except if (cond) expr1 else expr2) which takes an atomic element as argument but returns vector since ifelse returns an object of the same length as its argument?
x = c(1,2,3)
y = c(4,5,6,7)
z = 3
ifelse(z <= 3,x,y)
would return x and not 1
thanks
2006 Oct 27
2
all.names() and all.vars(): sorting order of functions' return vector
Dear list-subscriber,
in the process of writing a general code snippet to extract coefficients
in an expression (in the example below: 0.5 and -0.7), I stumbled over
the following peculiar (at least peculiar to me:-) ) sorting behaviour
of the function all.names():
> expr1 <- expression(x3 = 0.5 * x1 - 0.7 * x2)
> all.names(expr1)
[1] "-" "*" "x1"
2006 Jul 18
2
I think this is a bug
Hello!
I work with:
R : Copyright 2006, The R Foundation for
Statistical Computing
Version 2.3.1 (2006-06-01)
On Windows XP Professional (Version 2002) SP2
I think there is a bug in the conditional
execution if (expr1) {expr2} else {expr3}
If I try:
"if (expr1) expr2 else expr3"
it works well but when I put the expression expr2
and expr3 between {} I receive an error message
2003 Jan 31
2
Varying texts in expression(paste())
Hi,
I am using R a lot to make plots relating to radioactivity, I am often using
expression() to label the plots with nuclide names written with
superscripts, e.g.
expression(paste("Releases of ", { }^{99},Tc," (TBq/year)"))->ywtext
But, is there any simple way to change the number and name of the nuclide
through a variable? I tried
nuccode=expression({ }^{99},Tc)
2014 May 01
3
How to test if an object/argument is "parse tree" - without evaluating it?
This may have been asked before, but is there an elegant way to check
whether an variable/argument passed to a function is a "parse tree"
for an (unevaluated) expression or not, *without* evaluating it if
not?
Currently, I do various rather ad hoc eval()+substitute() tricks for
this that most likely only work under certain circumstances. Ideally,
I'm looking for a isParseTree()
2004 Jul 12
8
Gogoif with variables acting funny?
Using an example provided by "The Hitchhiker's Guide to Asterisk", I
made the following addition to my extensions.conf file:
[inbound-analog]
exten => s,1,Wait(1)
exten => s,2,SetVar(counter=0)
exten => s,3,Answer()
exten => s,4,Wait(1)
exten => s,5,DigitTimeout(15)
exten => s,6,ResponseTimeout(10)
2005 Jun 03
2
Everyone-- the scoop on Bison/Flex --
Hey, everybody---
Ignorance CAN be bliss, at least for a while, but, .... Just so you
know...
A week or two ago, some upgrades to the expression parser (you know, the
expressions you put in $[ ... ] in your extensions.conf file) that I
submitted, have been merged into the CVS HEAD of the source.
Hopefully, for around 99.9% of you, it won't make any difference to you.
The Makefile has also
2013 Feb 04
2
Modifying a function programmatically
Dear list
# I have a function
ff <- function(a,b=2,c=4){a+b+c}
# which I programmatically want to modify to a more specialized function in which a is replaced by 1
ff1 <- function(b=2,c=4){1+b+c}
# I do as follows:
vals <- list(a=1)
(expr1 <- as.expression(body(ff)))
expression({
a + b + c
})
(expr2 <- do.call("substitute", list(expr1[[1]], vals)))
{
1 +
2002 Aug 07
2
Constructing titles from list of expressions
Hello!
I have the following problem:
I have a function to construct three surfaceplots with a marker for an optimum,
each of the plots has as title paste("Estimated ",pred.var.lab," for
",var.lab[1]," vs. ",var.lab[2],sep="") with different var.lab[1,2] each time.
My problem is now that I need to allow for plotmath expressions in the
variables pred.var.lab
1997 Apr 30
2
R-beta: Small problems with R0.49
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2023 Jan 11
1
return value of {....}
I am more than a little puzzled by your question.
In the construct {expr1; expr2; expr3} all of the
expressions expr1, expr2, and expr3 are evaluated,
in that order. That's what curly braces are FOR.
When you want some expressions evaluated in a
specific order, that's why and when you use curly
braces. If that's not what you want, don't use them.
Complaining about it is like
2009 May 10
4
Partial Derivatives in R
Quick question:
Which function do you use to calculate partial derivatives from a model
equation?
I've looked at deriv(), but think it gives derivatives, not partial
derivatives. Of course my equation isn't this simple, but as an example,
I'm looking for something that let's you control whether it's a partial or
not, such as:
somefunction(y~a+bx, with respect to x,
2001 May 30
2
environments
I would like to be able, inside a function, to create a new function, and
use it as part of a formula as an argument to, say, gnls or nlme. for
example:
MyTop <- function(data=dta) {
Cexp <- function(dose,A,B,m){...}
Model <- as.formula(paste("y","~ Cexp(",paste(formals(Cexp),collapse
=", "),")"))
MyCall <-
2009 Oct 19
2
How to get slope estimates from a four parameter logistic with SSfpl?
Hi,
I was hoping to get some advice on how to derive estimates of slopes from four parameter logistic models fit with SSfpl.
I fit the model using:
model<-nls(temp~SSfpl(time,a,b,c,d))
summary(model)
I am interested in the values of the lower and upper asymptotes (parameters a and b), but also in the gradient of the line at the inflection point (c) which I assume tells me my rate of
2011 Aug 28
1
read.table: deciding automatically between two colClasses values
Hello,
I have a function for reading a data-frame from a file, which contains
E = read.table(file = filename,
header = T,
colClasses = c(rep("integer",6),"numeric","integer",rep("numeric",8)),
...)
Now a small variation arose, where
colClasses =
2014 Sep 12
3
[LLVMdev] poison and select
> Poison is a flawed concept. I proved it was flawed back in 2011 [0]
Nice. My colleagues and I will dig through this material and possibly come
back with some ideas. We're going to need some sort of semantics for UB in
LLVM since otherwise these formal-methods-based tools like Souper and
Alive risk not making sense.
Thanks,
John
2014 Sep 19
2
[LLVMdev] poison and select
Today I ran into another aspect of the poison problem...
Basically, SimplifyCFG wants to take
expr1 && expr2
and flatten it into
x = expr1
y = expr2
x&y
This isn't safe when expr2 might execute UB. The consequence is that no
LLVM shift instruction is safe to speculatively execute, nor is any
nsw/nuw/exact variant, unless the operands can be proven to be in
2009 Dec 01
1
Adding and Multiplying two Unevaluated Expressions
HI,
As I'm trying to compute Taylor series, I'm having problems in adding and multiplying unevaluated expressions. I searched for a solution but found none.
my Taylor function works fine for evaluating functions as you can see here:
rTaylorVal=function(exp,x0,dx,n) {
ls=list(x=x0)
newexp=eval(exp,ls)
exp0=exp
for (i in 1:n){
exp0=D(exp0,"x")
2012 Aug 07
4
Execution of a function
Hi
>i have aproblem withe execution of my function
>first, i wrote my function in the script of R
>nom_fonction <- function(arg1[=expr1], arg2[=expr2], ...){
bloc d'instructions
}
> when i want to have the result i mean the laste instruction in the bloc of
> instruction , i try to
>wrote the name of function
>source(aj.fun)
Error in readLines(file, warn =
2023 Jan 13
1
return value of {....}
R's
{ expr1; expr2; expr3}
acts much like C's
( expr1, expr2, expr3)
E.g.,
$ cat a.c
#include <stdio.h>
int main(int argc, char* argv[])
{
double y = 10 ;
double x = (printf("Starting... "), y = y + 100, y * 20);
printf("Done: x=%g, y=%g\n", x, y);
return 0;
}
$ gcc -Wall a.c
$ ./a.out
Starting... Done: x=2200, y=110
I don't like that