Displaying 20 results from an estimated 3000 matches similar to: "imputation of sub-threshold values"
2004 Mar 11
3
making operators act on rows of a data frame
Dear R helpers,
I wish to use the "sum" operator for each row of a data frame.
However, it appears that the operator acts on the entire data
frame, over all columns. What is the best way to obtain row-
wise operation?
The following code shows my attempts so far, and their problems:-
test1=array(rbinom(120,1,0.5),c(20,3))
test1[,3]=NA
sum(test1[,1:2])
test1[,3][sum(test1[,1:2])>=2]=1
2003 Dec 30
1
odd results from polr vs wilcoxon test
Dear R helpers,
I would like to ask why polr occasionally generates results that look very
odd.
I have been trying to compare the power of proportional odds logistic
regression with
the Wilcoxon test. I generated random samples, applied both tests and
extracted and
compared the p-values, thus:-
library(MASS)
c1=rep(NA,100); c2=c1
for (run in 1:100)
{
dat=c(rbinom(20,12,0.65),rbinom(20,12,0.35))
2003 Jan 20
2
Too many e-mails
Oh dear - I joined the R help mailing list last week,
in order to ask a specific question. I did not realise
that I would start to receive all e-mails to and from
the mailing list. Is there a way of letting me receive
only the answers to my own questions? If not, then can
you remove me from the mailing list?
Thanks,
Jonathan Williams
Jonathan Williams
OPTIMA
Radcliffe Infirmary
Woodstock Road
2003 Jan 17
1
Survr error
I am trying to analyse recurrent failure times using survfitr
from the survrec package. To do this, I need to "Create a survival
recurrent object" using Survr. But, when I do this, I get an error
"Error in Survr(r1d[, 1], r1d[, 5], r1d[, 6]) : data doesn't match".
Here, r1d[,1] is the identifier for each case, r1d[,5] is the time
of recurrence, r1d[,6] is the status
2004 May 27
2
Is it possible to read jpeg files into R?
Hi Helpers,
Does anyone know how to read jpeg, bmp or png files into R?
I have some photos of brain scans and I want to quantify
some aspects of their size. I might be able to do this
with the 'locator' function, if I could figure out how
to read the files in and make them into an image that
I can display on the R Windows device. I have experimented
with readBin, using a simple
2004 Mar 19
2
How to collect trees grown by rpart
Jonathan,
Try making a list instead of an array. See ?list. Also, did you look into
random forests? I'm not sure what you want to do, but there might be
methods there to do some of the work for you.
Sean
On 3/19/04 1:12 PM, "Jonathan Williams"
<jonathan.williams at pharmacology.oxford.ac.uk> wrote:
> I would like to collect the trees grown by rpart fits in an array,
2003 Feb 13
1
(no subject)
Dear R helpers,
I have a curious problem, which is that a program I have written in R
crashes R, unpredictably. When I say that the program crashes R, I mean
that it causes R to terminate, completely. But, the operating system
(Windows) continues OK.
The program loops around a randomForest regression. I am trying to use
randomForest to predict the diagnosis for a set of patients with dementia.
I
2003 Feb 13
0
(no subject)
Jonathan,
Is there any possibility for you to send me the data, and/or the code? I
and others have seen similar problems before, but not reproducible on the
current version, at least on the NT and Linux boxes that I have access to.
As Thomas said, it's difficult to nail these kinds of problems. Having
reproducible data and code, at least, can help. (It's no help that I'm no
expert
2003 Aug 11
0
Designing and incorporating a digital filter
I have a time series of data from an electroencephalogram (EEG).
I wish to filter the data to get rid of 50Hz mains 'hum'. I have
'designed' a combination bandpass and notch filter using a web-
site. The site returns the filter in "ANSI C" source code. It is:-
/* Digital filter designed by mkfilter/mkshape/gencode A.J. Fisher
Command line:
2004 Apr 27
0
Extracting labels for residuals from lme
Dear R-helpers,
I want to try to extract residuals from a multi-level
linear mixed effects model, to correlate with another
variable. I need to know which residuals relate to
which experimental units in the lme. I can show the
labels that relate to the experimental units via the
command
ranef(fit0)$resid
which gives:
604/1/0 -1.276971e-05
604/1/1 -1.078644e-03
606/1/0 -7.391706e-03
606/1/1
2004 Feb 19
3
suppressing non-integer labels for plot x-axis
Dear R-helpers,
I am having difficulty making R plot only integer labels on the x-axis
of a simple graph. I want to plot the median values of a score on each
of three occasions. Non-integer occasions are impossible. But, R keeps
labelling the x-axis with half-occasions, despite my attempts to stop
this using the "xaxs" and "xaxp" parameters of 'plot'.
p1=c(1,2,3);
2003 May 19
1
plotting a simple graph
I am having great difficulty plotting what should be a simple graph.
I have measured 1 'y' and 5 'x' variables in each of two groups.
Linear regression shows significant differences in the slopes of the
regression for each 'x' variable between the two groups.
All that I want to do is to plot one graph that shows the scatterplot
for the three groups (each group represented
2004 Apr 27
3
R hang-up using lm
Dear R-helpers,
I have found a slightly annoying problem when trying to
plot lines on graphs. I first created my data using
tapply, thus:-
y1=as.vector(fit1$coef$random$id)
x1=tapply(o1,id,median,na.rm=T)
x2=tapply(o2,id,median,na.rm=T)
#then I plot the data, thus:-
plot(x1[x2==0],y[x2==0])
#if I now try to fit the linear regression, R 'hangs up'
2008 Jun 30
3
Is there a good package for multiple imputation of missing values in R?
I'm looking for a package that has a start-of-the-art method of
imputation of missing values in a data frame with both continuous and
factor columns.
I've found transcan() in 'Hmisc', which appears to be possibly suited
to my needs, but I haven't been able to figure out how to get a new
data frame with the imputed values replaced (I don't have Herrell's book).
Any
2003 Dec 08
1
Design functions after Multiple Imputation
I am a new user of R for Windows, enthusiast about the many functions
of the Design and Hmisc libraries.
I combined the results of a Cox regression model after multiple imputation
(of missing values in some covariates).
Now I got my vector of coefficients (and of standard errors).
My question is: How could I use directly that vector to run programs such
as 'nomogram', 'calibrate',
2008 Nov 26
1
multiple imputation with fit.mult.impute in Hmisc - how to replace NA with imputed value?
I am doing multiple imputation with Hmisc, and
can't figure out how to replace the NA values with
the imputed values.
Here's a general ourline of the process:
> set.seed(23)
> library("mice")
> library("Hmisc")
> library("Design")
> d <- read.table("DailyDataRaw_01.txt",header=T)
> length(d);length(d[,1])
[1] 43
[1] 2666
2011 Feb 07
1
multiple imputation manually
Hi,
I want to impute the missing values in my data set multiple times, and then
combine the results (like multiple imputation, but manually) to get a mean
of the parameter(s) from the multiple imputations. Does anyone know how to
do this?
I have the following script:
y1 <- rnorm(20,0,3)
y2 <- rnorm(20,3,3)
y3 <- rnorm(20,3,3)
y4 <- rnorm(20,6,3)
y <- c(y1,y2,y3,y4)
x1 <-
2010 Aug 10
1
Multiple imputation, especially in rms/Hmisc packages
Hello, I have a general question about combining imputations as well as a
question specific to the rms and Hmisc packages.
The situation is multiple regression on a data set where multiple
imputation has been used to give M imputed data sets. I know how to get
the combined estimate of the covariance matrix of the estimated
coefficients (average the M covariance matrices from the individual
2003 Jul 27
1
multiple imputation with fit.mult.impute in Hmisc
I have always avoided missing data by keeping my distance from
the real world. But I have a student who is doing a study of
real patients. We're trying to test regression models using
multiple imputation. We did the following (roughly):
f <- aregImpute(~ [list of 32 variables, separated by + signs],
n.impute=20, defaultLinear=T, data=t1)
# I read that 20 is better than the default of
2005 May 04
3
Imputation
I have timeseries data for some factors, and some missing values are there in those factors, I want impute those missing values without disturbing the distribution of that factor, and maintaining the correlation with other factors. Pl. suggest me some imputation methods.
I tried some functions in R like aregImpute, transcan. After the imputation I am unable to retrive the data with imputed