Displaying 20 results from an estimated 11000 matches similar to: "Randomly generating data"
2012 Jun 18
6
Trying to speed up an if/else statement in simulations
Dear R-help,
I am trying to write a function to simulate datasets of size n which contain
two time-to-event outcome variables with associated 'Event'/'Censored'
indicator variables (flag1 and flag2 respectively). One of these indicator
variables needs to be dependent on the other, so I am creating the first and
trying to use this to create the second using an if/else statement.
2010 May 23
2
Bernoulli random variable with different probability
Dear R-helpers,
I would like to generate a variable that takes 0 or 1, and each subject has
different probabilities of taking the draw.
So, which of the following code I should use ?
suppose there are 5 subjects, and their probabilities of this Bernoulli
variable is p=c(0.2, 0.9, 0.15, 0.8, 0.75)
n<-5
Ber.var <- rbimon(n,1,p) ## I doubt if this will take the first probability,
which is
2011 Jul 02
1
Simulating inhomogeneous Poisson process without loop
Dear all
I want to simulate a stochastic jump variance process where N is Bernoulli
with intensity lambda0 + lambda1*Vt. lambda0 is constant and lambda1 can be
interpreted as a regression coefficient on the current variance level Vt. J
is a scaling factor
How can I rewrite this avoiding the loop structure which is very
time-consuming for long simulations?
for (i in 1:N){
...
N <- rbinom(n=1,
2006 Jun 27
2
Random numbers negatively correlated?
Dear list,
I did simulations in which I generated 10000
independent Bernoulli(0.5)-sequences of length 100. I estimated
p for each sequence and I also estimated the conditional probability that
a one is followed by another one (which should be p as well).
However, the second probability is significantly smaller than 0.5 (namely
about 0.494, see below) and of course smaller than the direct
2011 Apr 26
6
Tell the difference between characters
Dear all,
I just want to determine if the characters in a character string are the
same or not. For example,
temp <- c("aa", "aA", "ab")
How do I determine the first one have the two same ?a?, and the second and
third have the different characters? Thanks in advance.
Lisa
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2007 Jul 03
3
generating correlated Bernoulli random variables
Hi all,
I was wondering how to generate samples for two RVs X1 and X2.
X1 ~ Bernoulli (p1)
X2 ~ Bernoulli (p2)
Also, X1 and X2 are correlated with correlation \rho.
Regards,
Vineet
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2010 Jan 25
5
Data transformation
Dear all,
I have a dataset that looks like this:
x <- read.table(textConnection("col1 col2
3 1
2 2
4 7
8 6
5 10"), header=TRUE)
I want to rewrite it as below:
var1 var2 var3 var4 var5 var6 var7 var8 var9 var10
1 0 1 0 0 0 0 0 0 0
0 2 0 0 0 0 0 0 0 0
0 0 0 1 0 0
2011 Apr 27
4
Pause the execution of a function
Dear all,
I am trying to write a script to pause the execution of a function and
provide some additional commands to the function and then continue execution
of the function. For example, when my function detects a wrong number in a
dataset, the function pauses automatically and returns information on the
screen:
?There is a wrong number in the dataset. Would you like to correct it? ?
If I
2009 Mar 28
1
Error in R??
Can someone explain why I am getting the following error: in the r code
below?
Error in solve.default(diag(2) + ((1/currvar) * (XX1 %*% t(XX1)))) :
system is computationally singular: reciprocal condition number = 0
In addition: There were 50 or more warnings (use warnings() to see the first
50)
The R code is part of a bigger program.
##sample from full conditional
2010 Jan 08
4
Arguments of a function
Dear all,
I have a question about how to set arguments in my own function. For
example, I have a function that looks like this:
my.f <- function(a = x1, b = x2)
{
x1 = equation 1
x2 = equation 2
x3 = equation 3
y = a + b
}
x1, x2, and x3 are temporary variables (intermediate results) calculated
from other variables within the funciton. I want to use two of these three
2009 Dec 03
3
dataset index
Hello, All,
I have a dataset that looks like this:
x <- matrix(c(
0, 0, 0,
0, 0, 0,
0, 1, 0,
0, 1, 0,
0, 1, 0,
1, 2, 1,
1, 2, 1,
1, 3, 1,
1, 3, 1,
1, 3, 1),
ncol = 5, byrow = T,
dimnames = list(1:10, c("gender", "race", "disease")))
I want to write a function to produce several matrices including only ?TRUE?
and ?FALSE? for the different levels of the
2010 Apr 26
3
R.GBM package
HI, Dear Greg,
I AM A NEW to GBM package. Can boosting decision tree be implemented in
'gbm' package? Or 'gbm' can only be used for regression?
IF can, DO I need to combine the rpart and gbm command?
Thanks so much!
--
Sincerely,
Changbin
--
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2008 Jan 02
1
Random Bernoulli sequences with given point-biserial correlation?
Dear R-listers,
Can someone suggest a method for generating a finite Bernoulli
sequence that is likely to have a given point-biserial correlation
with an existing Bernoulli sequence?
_____________________________
Professor Michael Kubovy
University of Virginia
Department of Psychology
USPS: P.O.Box 400400 Charlottesville, VA 22904-4400
Parcels: Room 102 Gilmer Hall
2010 Jan 25
2
Delete components of a list
Dear all,
I have a question about deleting components of a list. For example, I have a
list that looks like this:
[[1]]
var1 var2 var3
1 3 4
2 2 1
[[2]]
var1 var2 var3
2 5 1
2 1 7
[[3]]
var1 var2 var3
1 6 7
3 8 4
How to delete, say, the first columns of the list or the second rows? Thank
in advance.
Lisa
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2011 Jun 01
5
Recode numbers
Dear all,
I have two sets of numbers that look like
a <- c(1, 2, 3, 3, 4, 4, 5, 6, 1, 2, 2, 3, 1, 2, 1, 2, 3, 3, 4, 5, 1, 2, 3,
4)
b <- c(1, 5, 8, 9, 14, 20, 3, 10, 12, 6, 16, 7, 11, 13, 17, 18, 2, 4, 15,
19)
I just want to use ?b? to encode ?a? so that ?a? looks like
a1<- c(1, 5, 8, 8, 9, 9, 14, 20, 3, 10, 10, 12, 6, 16, 7, 11, 13, 13, 17,
18, 2, 4, 15, 19)
Does anyone have a
2009 Dec 15
2
Reconstruct a dataset
Dear all,
I have a dataset that looks like this:
inividual var1 var2 ?
1 1 1 ?
2 1 2 ?
3 2 1 ?
4 2 2 ?
? ? ? ?
I will random sample 2 individuals from this dataset based on a set of
random numbers, e.g.,
rn1 <- c(0, 0, 1, 1), rn2 <- c(0, 0, 2, 0), rn3 <- c(1, 0, 0, 1), rn4 <-
2011 May 26
3
Suppress intermediate results on console
Dear all,
I have a question about how to suppress intermediate results in a function
on console. For example, I will use summary() in my own function that looks
like:
myfunction <- function(?)
{
?
Summary(x)
?
}
Then myfunction() will print ?x? on console that is intermediate result and
doesn?t need showing.
Does someone have any idea or any suggestion? Thank you in advance.
Lisa
2009 Dec 04
1
User's function
Hello, All,
I want to write a function to do some works based on the arguments. For
example, bind some variables (arguments) as this:
myfunction <- function(arg1, arg2, arg3, ?)
{
x <- cbind(arg1, arg2, arg3, ?)
}
myfunction(arg1, arg2, arg3, ?)
The function can automatically determine the number of arguments and bind
them, which means if I assign 2 arguments, the function can bind
2011 Mar 18
3
Arguments of a function
Hi, everybody,
I just want to pass arguments to a function as below:
range <- c(0.1, 0.5)
runif(1, range)
But it doesn?t work.
Does anyone have any suggestions to offer?
Thanks.
Lisa
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2011 Feb 01
1
Lmer binomial distribution x HLM Bernoulli distribution
Dear R-users,
I'm running a lmer model using the lme4 package. My dependent variable is
dichotomous and I'm using the "binomial" family. The results
are slightly different from the HLM results based on a Bernoulli
distribution. I read that a Bernoulli distribution is an extension of a
binomial distribution. Is that right? If so, how can I adapt my R model to a
Bernoulli