Displaying 20 results from an estimated 10000 matches similar to: "Generate data - function"
2009 Apr 08
3
MLE for bimodal distribution
Hello everyone,
I'm trying to use mle from package stats4 to fit a bi/multi-modal
distribution to some data, but I have some problems with it.
Here's what I'm doing (for a bimodal distribution):
# Build some fake binormally distributed data, the procedure fails also with
real data, so the problem isn't here
data = c(rnorm(1000, 3, 0.5), rnorm(500, 5, 0.3))
# Just to check
2009 Dec 15
1
Help in R
Hello,
Can anyone give me some suggestion in term of calculating the sum below.
Is there a function in R that can help doing it faster?
x1, x2, ...xn where xi can be 0 or 1. I want to calculate the following:
sum{ beta[a+sum(xi), b+n-sum(xi) ]* [ (1-x1)dnorm(0,1)+x1dnorm(2,1) ]* [
(1-x2)dnorm(0,1)+x2dnorm(2,1) ]* ...* [ (1-xn)dnorm(0,1)+xndnorm(2,1) ] }
The sum in the beginning is over all
2006 Sep 27
3
t-stat Curve
Number of subjects = 25
Mean of Sample = 77
Standard Deviation (s) = 12
sem = 2.4
df = 24
The claim is that population mean is less than 80
* > 80
So our H0 (null hupotheis) is * > 80
> qt(.95,24)
[1] 1.710882
> qt(0.05, 24)
[1] -1.710882
tstat = -1.25 on t24 falls between 1.711 (.95,24) and *1.711 (.005,24)
How Could I sketch t curve for the above data where my * would be at the
2004 Sep 16
3
Estimating parameters for a bimodal distribution
For several years, I have been using Splus to analyze an ongoing series of
datasets that have a bimodal distribution. I have used the following
functions, in particular the ms() function, to estimate the parameters: two
means, two standard deviations, and one proportion. Here is the code I've
been using in S:
btmp.bi <- function(vec, p, m1, m2, sd1, sd2)
{
2007 Feb 23
4
How to plot two graphs on one single plot?
Hi,
I am trying to plot two distribution graph on one plot. But I dont know
how. I set them to the same x, y limit, even same x, y labels.
Code:
x1=rnorm(25, mean=0, sd=1)
y1=dnorm(x1, mean=0, sd=1)
x2=rnorm(25, mean=0, sd=1)
y2=dnorm(x2, mean=0, sd=1)
plot(x1, y1, type='p', xlim=range(x1,x2), ylim=range(y1, y2), xlab='x',
ylab='y')
plot(x2, y2, type='p',
2003 Apr 10
1
how to estimate parameters of multimodal distribution
Dear all
Please, is there any function or package for dealing with multimodal distributions?
I try to fit multimodal distribution or more precisely to find out mixture of normal
distributions which can lead to my actual data.
I use optim to find (in that case) two parameters but what I want is to let the
function find out arbitrary number of normal distributions underlaying my actual
data
2001 May 10
3
lookup function for density(...) objects
Hi folks:
Is there a lookup function that returns the variate given the cumulative
probability for an object returned by the density(...) function?
> mydata _ as.vector(mymatrix)
> mydata.density _ density(mydata)
> mydata.p80 _ lookup(mydata.density, p=0.8) # is there any function to
accomplish this task?
Thanks.
Rajiv.
--------
Rajiv Prasad, Postdoctoral Research Associate,
2010 Sep 05
1
Add y-title to a plot with two y axis
Hi all,
We managed to plot two series on the same graph, with two y-axis,
however, we haven't managed to add a title to the second y-axis
x1=rnorm(25, mean=0, sd=1)
y1=dnorm(x1, mean=0, sd=1)
x2=rnorm(25, mean=0, sd=1)
y2=dnorm(x2, mean=0, sd=1)
plot(x1, y1, type='p', xlab='x', ylab='y')
par(new=TRUE)
plot(x1, y2, type='p', axes= FALSE,
2007 Oct 13
2
How to identify the two largest peaks in a trimodal distribution
Hello all
I'm trying to do a simulation that involves identifying the minimum
point between two peaks of a (usually) bimodal distribution. I can do
this easily if there are only two peaks:
CnBdens<-density(Ys/Xs) #probability density function for ratio of Ys
to Xs
for(p in 1:512) ifelse(CnBdens$y[p]>CnBdens$y[p-1],peak1<-p,break)
#identifies first peak in probability
2000 Jan 12
1
Usage of p/d/qnorm
Hello,
could You please help: I am looking for a way to formulate test accuracy
measures such as test sensitivity, specificity, predictive values, and
correct classification rate using p/d/qnorm. The tests' primary values
follow a bimodal distribution, which is modelled by a mixture of two normal
distributions:
p * dnorm ((x - u1) / s1) / s1 +
(1 - p) * dnorm ((x - u2) / s2) / s2)
2007 Mar 25
1
eliminating panel borders from lattice plots
I am trying to eliminate panel borders from my
lattice plots. By default, they always print. For
example:
library(lattice)
x <- seq(-3,3,length=1000)
y1 <- dnorm(x)
y2 <- dnorm(x, sd=.5)
data <- data.frame(x=rep(x,2), y=c(y,y2),
panel=rep(c(1,2), each=1000))
dplot <- xyplot(y~x | panel, data=data, strip=F,
scales=list(draw=F))
2013 Mar 18
2
Fit a mixture of lognormal and normal distributions
Hello
I am trying to find an automated way of fitting a mixture of normal and log-normal distributions to data which is clearly bimodal.
Here's a simulated example:
x.1<-rnorm(6000, 2.4, 0.6)x.2<-rlnorm(10000, 1.3,0.1)X<-c(x.1, x.2)
hist(X,100,freq=FALSE, ylim=c(0,1.5))lines(density(x.1), lty=2, lwd=2)lines(density(x.2), lty=2, lwd=2)lines(density(X), lty=4)
Currently i am using
2018 Feb 25
3
include
Thank you Jim,
I read the data as you suggested but I could not find K1 in col1.
rbind(preval,mydat) Col1 Col2 col3
1 <NA> <NA> <NA>
2 X1 <NA> <NA>
3 Y1 <NA> <NA>
4 K2 <NA> <NA>
5 W1 <NA> <NA>
6 Z1 K1 K2
7 Z2 <NA> <NA>
8 Z3 X1 <NA>
9 Z4 Y1 W1
On Sat, Feb 24, 2018 at 6:18 PM, Jim
2007 Mar 08
2
curve of density on histogram
Hi R users,
I would like to know why these following curve densities don't appear
correctly on the histograms.
Thank you for your help
library(lattice)
library(grid)
resp <- rnorm(2000)
group <- sample(c("G1", "G2", "G3", "G4"), replace = TRUE, size = 1000)
histogram(~ resp | group, col="steelblue",
panel = function(x, ...){
std
2007 Jun 25
3
How to shadow 'power' area?
Dear all,
Suppose I plot two normal distributions (A and B) side by side and add
vertical line which hipotheticaly represent alpha value; e.g.:
x <- seq(-3.5,5, length=1000)
y <- dnorm(x)
# Plot distribution A
plot(y~x, type='l',axes=F,xlab="",ylab="",lwd=2)
# Plot distribution B
y2 <- dnorm(x-1.5)
lines(y2~x,lwd=2)
# Plot vertical line for alpha value
2018 Feb 25
2
include
HI Jim and all,
I want to put one more condition. Include col2 and col3 if they are not
in col1.
Here is the data
mydat <- read.table(textConnection("Col1 Col2 col3
K2 X1 NA
Z1 K1 K2
Z2 NA NA
Z3 X1 NA
Z4 Y1 W1"),header = TRUE,stringsAsFactors=FALSE)
The desired out put would be
Col1 Col2 col3
1 X1 0 0
2 K1 0 0
3 Y1 0 0
4 W1 0 0
6 K2 X1
2010 Mar 20
2
EM algorithm in R
Please help me in writing the R code for this problem. I've been solving this
for 4 days. It was hard for me to solve it. It's a simulation problem in R.
The problem is
My true model is a normal mixture which is given as
0.5 N(-0.8,1) + 0.5 N(0.8,1). This model has two components.
I will get a random sample of size 100 from this model. I will do this 300
times.
That means, I will have
2006 Mar 21
1
Simulate Mixture Model data
Dear R Users??
I woould like to generate mixture model data.
I try two type method as followings two method, can anyone tell me which is right? or better?
1. generate two vectors data y1 and y2 from f1 and f2 seperately, and calculate y=alpha1*y1+alpha2*y2,
2. generate prob=unif(1), if prob <alpha1 y=y1, else y=y2.
Can anyone give me some idea?
Thanks so much!
Goeland
goeland at
2018 Feb 25
0
include
Hi Val,
My fault - I assumed that the NA would be first in the result produced
by "unique":
mydat <- read.table(textConnection("Col1 Col2 col3
Z1 K1 K2
Z2 NA NA
Z3 X1 NA
Z4 Y1 W1"),header = TRUE,stringsAsFactors=FALSE)
val23<-unique(unlist(mydat[,c("Col2","col3")]))
napos<-which(is.na(val23))
preval<-data.frame(Col1=val23[-napos],
2018 Feb 25
2
include
Sorry , I hit the send key accidentally here is my complete message.
Thank you Jim and all, I got it.
I have one more question on the original question
What does this "[-1] " do?
preval<-data.frame(Col1=unique(unlist(mydat[,c("Col2","col3")]))[-1],
Col2=NA,col3=NA)
mydat <- read.table(textConnection("Col1 Col2 col3
Z1 K1 K2
Z2