Displaying 20 results from an estimated 600 matches similar to: "Problems with randomly generating samples"
2009 May 13
11
Simulation
Dear R users,
Can anyone please tell me how to generate a large number of samples in R, given certain distribution and size.
For example, if I want to generate 1000 samples of size n=100, with a N(0,1) distribution, how should I proceed?
(Since I dont want to do "rnorm(100,0,1)" in R for 1000 times)
Thanks for help
Debbie
2008 Feb 29
1
write.csv +RMySQL request
Hello,
I am relatively new to R and learning its ins and outs. As part of a website I am building, I need to read and write csv files directly from an SQL database. Basically I want to convert R variables (dataframes) into CSV format, store them as another R variable (as a properly formatted text string suitable for csv reading) and then send this to one row in a database.
The SQL part is fine,
2009 May 16
1
Gamma function
Hi Guy,
I am having trouble graphing the following function
√2Γ(n/2)/[√n − 1Γ((n − 1)/2 for the values of n between 2 and 50.
i know that Γ(n) = (n-1)!, which in R is factorial(n-1)
When i type that into R, using y <- function(n).....
and then plot(y,2,50), it doesnt give me anything meaningful, in fact, it comes up with a message saying something like "in gamma(n+1) ploted" or
2008 May 20
1
The specified network name is no longer available 3.0.25 RHEL4
I have a reproducible intermittent error large site - "The specified network name is no longer available".
This happens when copying large files. Below is part of log level 10 output & strace. Sorry for the long posting. I will probably need to put the loglevel 10 attached to a bugzilla - but thought I would try the lists initially.
RHEL4
samba-3.0.25b-1.el4_6.4
2012 Nov 24
6
IMPORTANT!!!! PLEASE HELP ME
Hi,
I want to generate 10000 samples from normal distribution with replacement
case and every sample size is 50. What should I do ?
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2009 May 21
1
Need help on ploting Histograms
this is the command i made for a normal distribution, but when i try to plot
the histograms, i dont know why the bars don't stick on the line...
nsamples<-1000
sampsize<-15
Samples<-matrix(rnorm(nsamples*sampsize,0,1),nrow=nsamples)
a<-apply(Samples,1,var)
NC14<-a*14
x<-0:40
plot(x,dchisq(x,14),type='h')
hist(NC14,freq=F,add=T)
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2006 Nov 30
1
CAPI module issue
Hi List,
I am experiencing an issue in a server that I have installed asterisk;
configured an AVM FRITZ card to work with the capi module.
Once istalled the card works perfect; however every time I reboot the
machine I found that I have to re install the capi4k-utils before I can load
asterisk otherwise the capi module will not loadup.
Can anyone direct me in the right direction in order to
2009 May 18
3
(no subject)
Dear R users,
Based on a set of binomial sample data, how would you utilize the "nlm" function in R to estimate the true proportion of the population?
Thanks.
Debbie
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2009 May 12
2
Kumaraswamy distribution
Dear R users,
Does anyone know how to write function for Kumaraswamy distribution in R? Since I cannot write dkumar, pkumar, etc. in R.
Please help.
Thanks a lot,
Debbie
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2009 May 13
2
(no subject)
Dear R users,
Does anyone know how to graph the function below?
sqrt(2)Γ(n/2)/[sqrt(n − 1)Γ((n − 1)/2]
Please help.
Debbie
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2011 Feb 03
1
Double user name
I have two samba servers running Ubuntu 10.04 Samba Version 3.4.7
One server acts as domain controller and stores user ids in a .tdb
Somehow I've ended up with a duplicate user name.
On the Domain Controller
# pdbedit -w -L|grep debbie
debbie:1005:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:84DEC6FE3B018B0FB977EDDF5009742C:[U
]:LCT-4D4B086F:
On the other Server running winbind I get
#
2009 May 16
1
(no subject)
Dear R users,
Does anyone know how to write a function involving derivative?
i.e. I want to implementing Newton's method in R, so my function is something like
x<- x-y/y'
I am not sure how to write y' in my function. Can anyone help?
In addition, if I want to implementing newton's method several times, what code should I use?
Currently, I use the following code.
2003 May 21
3
How to create EXT3 file system image from directories?
Hi there,
Is there a utility to create an EXT3 file system image from directories?
Just like the mkfs.jffs2 which creates a JFFS2 file system image from
directories?
The "mke2fs -j" only creates the bare bone file system, what I want is to
build an image with pre-built content.
Thanks,
Debbie
2008 Mar 09
1
sampsize in Random Forests
Hi all,
I have a dataset where each point is assigned to a class A, B, C, or
D. Each point is also assigned to a study site. Each study site is
coded with a number ranging between 1-100. This information is stored
in the vector studySites.
I want to run randomForests using stratified sampling, so I chose the option
strata = factor(studySites)
But I am not sure how to control the number of
2006 Jan 25
1
imbalanced classes
Hi Andy,
I know this topic has been discussed before on the R-help, but I was
wondering if you could offer some advice specific to my application.
I'm using the R random forest package to compare two classes of data,
the number of cases in each class relatively low, 28 in class 1 and 9
in class 2. I'd really like to use R environment to analyze this data,
however I'm finding it
2011 Nov 01
1
Sample size calculations for one sided binomial exact test
I'm trying to compute sample size requirements for a binomial exact test.
we want to show that the proportion is at least 90% assuming that it is
95%, with 80% power so any asymptotic approximations are out of the
questions. I was planning on using binom.test to perform the simple test
against a prespecified value, but cannot find any functions for computing
sample size. do any exist?
2005 Oct 27
1
Repost: Examples of "classwt", "strata", and "sampsize" i n randomForest?
"classwt" in the current version of the randomForest package doesn't work
too well. (It's what was in version 3.x of the original Fortran code by
Breiman and Cutler, not the one in the new Fortran code.) I'd advise
against using it.
"sampsize" and "strata" can be use in conjunction. If "strata" is not
specified, the class labels will be used.
2011 Feb 03
1
problem with parLapply from snow
Hi,
The following function use to work, but now it doesn't giving the error
"> CallSnow(, 100)
Using snow package, asking for 2 nodes
2 slaves are spawned successfully. 0 failed.
Error in checkForRemoteErrors(val) :
2 nodes produced errors; first error: no applicable method for 'lapply' applied to an object of class "list"
".
Where this is the
2006 Nov 13
1
random forest regression
Dear all,
I am doing a regression in ramdomForest, using the option "sampsize" reduce
the number of records used to produce the randomForest object.
The manual says "For classification, if sampsize is a vector of the length
the number of strata, then sampling is stratified by strata, and the
elements of sampsize indicate the numbers to be drawn from the strata". I
need my
2009 Mar 20
2
randomForest
Hi!
I am dealing with random forest using R.
Is there a way to sample a fixed no.of rows from a dataset for use with
different trees in random Forest.
To be more clear, my data set contains 1500 rows, and I am growing 500 trees
in Random Forest
Is it possible to sample only 500 rows of data from the data set and use it
for different trees in the forest. I mean each tree of the forest should use