Displaying 20 results from an estimated 6000 matches similar to: "Numerical integration"
2011 Jan 03
7
Saving objects inside a list
Hello there,
any ideas on how to save all the objects on my workspace inside a list
object?
For example, say my workspace is as follows
ls()
[1] "x" "y" "z"
and suppose I want to put these objects inside a list object, say
object.list <- list()
without having to explicitly write down their names as in
object.list$x = x
object.list$y = y
object.list$z = z
Is
2010 Dec 13
2
Integration with LaTex and LyX
Hello,
Are there any packages which allow for a good integration between R and
LaTex / LyX? I'm interested mainly in automatic (automagic?) imports of
plots/graphics.
Thanks in advance and best regards,
Eduardo de Oliveira Horta
[[alternative HTML version deleted]]
2010 Nov 16
2
Vectors out of lists?
Hello there
I have a list, Y, and each component of that list is a real-valued function
(that is, Y[[i]](u) returns a number).
I was wishing to build the mean function and the first thing I thought of
was
Ybar<-function(u){
mean(Y[[1:n]](u))
}
but obviously this doesn't work, since Y[[1:n]] is not allowed at all.
Any elegant suggestions? I really would like to avoid something like
2010 Nov 27
3
Two time measures
Hello!
I have a csv file of intra-day financial data (5-min closing prices) that
looks like this: (obs - the dates are formated as day/month/year, as is
usual here in Brazil)
Date;Time;Close
01/09/2009;10:00;56567
01/09/2009;10:05;56463
01/09/2009;10:10;56370
##(goes on all day)
01/09/2009;16:45;55771
01/09/2009;16:50;55823
01/09/2009;16:55;55814
##(jumps to the subsequent day)
2011 Jan 05
3
Adding lines in ggplot2
Hello,
this is probably a recurrent question, but I couldn't find any answers that
didn't involve the expression "data frame"... so perhaps I'm looking for
something new here.
I wanted to find a code equivalent to
> x=sqrt(1:10)
> y=log(1:10)
> plot(1:10, x, type="lines", col="darkgreen")
> lines(1:10, y, col="red")
to use with
2010 Dec 23
1
Removing elements of a list object
Hello,
say I have an object
> x = list(first = 10, second = 20, third = "Yeah!")
and want to remove the $second element of that list. My first try was, of
course,
> rm(x$second)
which gave me the following error message
> Error in rm(x$second) : ... must contain names or character strings
Any ideas here, folks?
Best regards, and Merry Christmas!
Eduardo Horta
2009 Dec 18
1
Numerical Integration
Dear @ll. I have to calculate numerical integrals for triangular and trapezoidal figures. I know you can calculate the exactly, but I want to do it this way to learn how to proceed with more complicated shapes. The code I'm using is the following:
integrand<-function(x) {
print(x)
if(x<fx[1]) return(0)
if(x>=fx[1] && x<fx[2]) return((x-fx[1])/(fx[2]-fx[1]))
2010 Dec 27
2
Finding indexes of minum and maximum elements of an array
Hello there
I wish to get the "coordinates" of the minimum element of an array.
For example, if the array were
> H = array(c(8:5,1:4),dim=c(2,2,2))
> H
, , 1
[,1] [,2]
[1,] 8 6
[2,] 7 5
, , 2
[,1] [,2]
[1,] 1 3
[2,] 2 4
then
> min(H)
[1] 1
and
> max(H)
[1] 8
Say "idx" were the function I'm looking for. Then, what
2011 Feb 22
2
Plotting a functional time series
Hello,
I'm willing to plot a sequence of densities on a 3d graph, something like
-----------------------------------------------------------------
x <- sapply(1:10, function(i)rnorm(1000))
f <- sapply(1:10, function(i)density(x[,i], from=-5,to=5)$y)
grid <- density(x[,1], from=-5,to=5)$x
win.graph()
persp(grid1, 1:10, f,theta=-50, phi=30, d=2)
2012 Sep 25
1
how to pass a function to a function inside a function
Hi,
I'm trying to compile two functions into one function. the first funtion is
called 'fs' which is self-made function, another function is from the
built-in 'integration' function that is copy-paste-edited. If built
separatey, these functions work well. However that is not the case if
combines together, where certainly I made mistake somewhere when
constructing the code.
2010 Nov 15
3
Defining functions inside loops
Hello,
I was trying to define a set of functions inside a loop, with the loop index
working as a parameter for each function. Below I post a simpler example, as
to illustrate what I was intending:
f<-list()
for (i in 1:10){
f[[i]]<-function(t){
f[[i]]<-t^2+i
}
}
rm(i)
With that, I was expecting that f[[1]] would be a function defined by t^2+1,
f[[2]] by t^2+2 and so on.
2011 Nov 10
2
performance of adaptIntegrate vs. integrate
Dear list,
[cross-posting from Stack Overflow where this question has remained
unanswered for two weeks]
I'd like to perform a numerical integration in one dimension,
I = int_a^b f(x) dx
where the integrand f: x in IR -> f(x) in IR^p is vector-valued.
integrate() only allows scalar integrands, thus I would need to call
it many (p=200 typically) times, which sounds suboptimal. The
2013 Jul 16
2
Problem following an R bug fix to integrate()
I have been told by the CRAN administrators that the following code generated
an error on 64-bit Fedora Linux (gcc, clang) and on Solaris machines (sparc,
x86), but runs well on all other systems):
> fn <- function(x, y) ifelse(x^2 + y^2 <= 1, 1 - x^2 - y^2, 0)
> tol <- 1.5e-8
> fy <- function(x) integrate(function(y) fn(x, y), 0, 1,
2011 Jan 27
2
pdf greek letter typos
Hi there,
yet on the topic of greek letters and pdf plotting: when I run the
following code
pdf(file="temp.pdf")
mu=seq(from=-pi, to=pi, length=100)
plot(mu, sin(mu^2),
type="l",
xlab=expression(mu%in%(list(-pi,pi))),
ylab=expression(sin(mu^2)),
main=expression((list(mu,sin(mu^2)))))
dev.off()
I get a "proportional to" symbol in place of a
2010 Nov 16
2
Integrating functions / vector arithmetic
Hello,
I was trying to build some functions which I would like to integrate over an
interval using the function 'integrate' from the 'stats' package. As an
example, please consider the function
h(u)=sin(pi*u) + sqrt(2)*sin(pi*2*u) + sqrt(3)*sin(pi*3*u) + 2*sin(pi*4*u)
Two alternative ways to 'build' this function are as in f and g below:
coeff<-sqrt(1:4)
2011 Jan 11
1
Alphabetic labels on multi-plot graphics
Is there a way to achieve
lbl=c("a", "b", "c", "d")
par(mfrow=c(2,2), ann=FALSE)
for (t in 1:4){
plot(seq(from=1,to=2*pi,length=100),
sin(t*seq(from=1,to=2*pi,length=100)), type="l")
title(main=paste("(", lbl[t], ")", sep=""))
}
without having to use an object like 'lbl'?
More generally: is it possible
2011 Feb 19
1
Building an array from matrix blocks
Hello,
I've googled for a while and couldn't find anything on this topic: say
I have a matrix A and want to build matrices B1, B2,... using blocks
from A (or equivalently an array B with B[,,i] being a block from A),
and that I must sum the B[,,i]'s.
I've come up with this rather non-elegant code:
> n = 6
> p = 3
>
> A <- matrix(1:(n^2), n, n, byrow=TRUE)
>
2011 Jan 06
1
Cairo pdf canvas size
Hello,
I want to save a pdf plot using Cairo, but the canvas of the saved file
seems too large when compared to the actual plotted area.
Is there a way to control the relation between the canvas size and the size
of actual plotting area?
Thanks in advance, and best regards,
Eduardo Horta
[[alternative HTML version deleted]]
2010 Dec 06
3
0.5 != integrate(dnorm,0,20000) = 0
Hello:
The example "integrate(dnorm,0,20000)" says it "fails on many
systems". I just got 0 from it, when I should have gotten either an
error or something close to 0.5. I got this with R 2.12.0 under both
Windows Vista_x64 and Linux (Fedora 13); see the results from Windows
below. I thought you might want to know.
Thanks for all your work in creating
2009 Sep 23
1
Numerical integration problem
Hi there
I'm trying to construct a model of mortality risk in 2D space that
requires numerical integration of a hazard function, for which I'm using
the integrate function. I'm occasionally encountering parameter
combinations that cause integrate to terminate with error "Error in
integrate... the integral is probably divergent", which I'm not sure how
to interpret. The