Displaying 20 results from an estimated 1100 matches similar to: "Different length of objects"
2017 Nov 04
2
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hello Tyler,
I rephrase my previous mail, as follows:
In your example, T_i = X1:X2:X3. Let F_j = X3. (The numerical
variables X1 and X2 are not encoded at all.) Then T_{i(j)} = X1:X2,
which in the example is dropped from the model. Hence the X3 in T_i
must be encoded by dummy variables, as indeed it is.
Arie
On Thu, Nov 2, 2017 at 4:11 PM, Tyler <tylermw at gmail.com> wrote:
> Hi
2017 Nov 06
2
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hello Tyler,
You write that you understand what I am saying. However, I am now at
loss about what exactly is the problem with the behavior of R. Here
is a script which reproduces your experiments with three variables
(excluding the full model):
m=expand.grid(X1=c(1,-1),X2=c(1,-1),X3=c("A","B","C"))
model.matrix(~(X1+X2+X3)^3-X1:X3,data=m)
2017 Nov 02
2
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hello Tyler,
Thank you for searching for, and finding, the basic description of the
behavior of R in this matter.
I think your example is in agreement with the book.
But let me first note the following. You write: "F_j refers to a
factor (variable) in a model and not a categorical factor". However:
"a factor is a vector object used to specify a discrete
classification"
2012 May 13
1
how to write data using xlsReadWrite
Hai I'm Dee. I'm trying to write var data from these codes inside excel
file. My directory to store the data is *D:\FYP\image* .
these are my codes, can you help give an advice or idea with my problem:
l*ibrary("biOps")
library("waveslim")
library("xlsReadWrite")
x <- readTiff("D:\\FYP\\image\\SignatureImage\\user186g1.tif")
y <-
2017 Oct 27
2
Bug in model.matrix.default for higher-order interaction encoding when specific model terms are missing
Hello Tyler,
I want to bring to your attention the following document: "What
happens if you omit the main effect in a regression model with an
interaction?" (https://stats.idre.ucla.edu/stata/faq/what-happens-if-you-omit-the-main-effect-in-a-regression-model-with-an-interaction).
This gives a useful review of the problem. Your example is Case 2: a
continuous and a categorical regressor.
2012 May 13
4
write data using xlsReadWrite
Hai, I'm trying to write these var output data from these codes inside excel
file. My directory to store the data is
/D:\FYP\image /
but receive an error message :
/Error in write.xls(mydata, "D:\\FYP\\image.mydata.xls") :
object 'mydata' not found/
these are my codes, can you help give an advice or idea with my problem:
/library("biOps")
2012 Jun 04
2
paquete SPEI función thornthwaite
Hola eRReros.
Os lo explico con un ejemplo:
# Cargamos los paquetes y el ejemplo
install.packages("SPEI")
library("SPEI")
data(wichita)
# los primeros 12 datos
head(wichita,12)
# mi subset de los primeros 12 datos
meu<-wichita[c(1:12),]
meu
# como veis los valores de TMED son iguales en ambos dataframes.
# ahora viene el problema
# calculamos
2011 Mar 07
1
Associating the day of week to a daily xts object
I have the following xts objetct "temp"
> str(temp)
An ?xts? object from 2010-12-26 to 2011-03-05 containing:
Data: num [1:70, 1] 2.95 0.852 -0.139 1.347 2.485 ...
- attr(*, "dimnames")=List of 2
..$ : NULL
..$ : chr "t_n"
Indexed by objects of class: [POSIXct,POSIXt] TZ: GMT
xts Attributes:
NULL
> temp
t_n
2010-12-26
2005 Jun 10
1
Estimate of baseline hazard in survival
Dear All,
I'm having just a little terminology problem, relating the language used in
the Hosmer and Lemeshow text on Applied Survival Analysis to that of the
help that comes with the survival package.
I am trying to back out the values for the baseline hazard, h_o(t_i), for
each event time or observation time.
Now survfit(fit)$surv gives me the value of the survival function,
S(t_i|X_i,B),
2008 Jun 03
3
How to solve a non-linear system of equations using R
Dear R-list members,
I've had a hard time trying to solve a non-linear system (nls) of equations
which structure for the equation i, i=1,...,4, is as follows:
f_i(d_1,d_2,d_3,d_4)-k_i(l,m,s) = 0 (1)
In the expression above, both f_i and k_i are known functions and l, m and s
are known constants. I would like to estimate the vector d=(d_1,d_2,d_3,d_4)
which is solution
2012 May 13
2
Discrete choice model maximum likelihood estimation
Hello,
I am new to R and I am trying to estimate a discrete model with three
choices. I am stuck at a point and cannot find a solution.
I have probability functions for occurrence of these choices, and then I
build the likelihood functions associated to these choices and finally I
build the general log-likelihood function.
There are four parameters in the model, three of them are associated to
2006 Jan 25
0
Log-Likelihood 3d-plot and contourplot / optim() starting values
Hello,
i have coded the following loglikelihood-function
# Log-Likelihood-Funktion
loglik_jm<-function(N,phi,t) {
n<-length(t)
i<-seq(along=t)
s1<-sum(log(N-(i-1)))
s2<-phi*sum((N-(i-1))*t[i])
n*log(phi)+s1-s2
}
# the data
t<-c(7,11,8,10,15,22,20,25,28,35)
# now i want to do a 3d-plot and a contourplot in order to see at which
values of N and phi the loglikelihood
2012 Oct 29
0
why isn't integrate function working in a likelihood
Dear R users,
I have been trying to solve for mle's of a function that involves an
integral and I keep getting an error. I created an example to work on first
and even the simple example doesn't give me the mle's. I am getting the
error "Error in integrate(integrand, 0, Inf) : non-finite function value".
I divided my likelihood function into two parts, one part involves
2011 Aug 26
2
How to generate a random variate that is correlated with a given right-censored random variate?
Hi,
I have a right-censored (positive) random variable (e.g. failure times subject to right censoring) that is observed for N subjects: Y_i, I = 1, 2, ..., N. Note that Y_i = min(T_i, C_i), where T_i is the true failure time and C_i is the censored time. Let us assume that C_i is independent of T_i. Now, I would like to generate another random variable U_i, I = 1, 2, ..., N, which is
2012 Oct 18
7
summation coding
I would like to code the following in R: a1(b1+b2+b3) + a2(b1+b3+b4) +
a3(b1+b2+b4) + a4(b1+b2+b3)
or in summation notation: sum_{i=1, j\neq i}^{4} a_i * b_i
I realise this is the same as: sum_{i=1, j=1}^{4} a_i * b_i - sum_{i=j} a_i
* b_i
would appreciate some help.
Thank you.
--
View this message in context: http://r.789695.n4.nabble.com/summation-coding-tp4646678.html
Sent from the R
2011 Mar 14
1
Math characters in column heading using latex() in Hmisc
Hi Everybody
I want to print a latex table containing math characters in the column
heading
These are the formulae I want to use as column headings. It prints OK from
TeX
$\sum_{i}\sum_{j}C_{P,i,j,y}\times\mathit{FC}_{i}$, $XU_{alt,y}$, $n$,
$\bar{C}_{P,y}$
My plan was to create a character vector with these and later rbind the
values to them. When I create the vector like:
2003 Nov 10
5
Subsetting a list of vectors
Hi,
I'm trying to subset a list which contains variable length vectors.
What I want to do is extract (eg.) the 3rd item in each vector (with
length >= 3). At the moment I'm using sapply(list.of.vectors,
function(x) {x[3]}). The problem with this is that sapply returns a
list of the same length of list.of.vectors so I end up with a whole lot
of null entries from those vectors
2006 Dec 08
1
MAXIMIZATION WITH CONSTRAINTS
Dear R users,
I?m a graduate students and in my master thesis I must
obtain the values of the parameters x_i which maximize this
Multinomial log?likelihood function
log(n!)-sum_{i=1]^4 log(n_i!)+sum_
{i=1}^4 n_i log(x_i)
under the following constraints:
a) sum_i x_i=1,
x_i>=0,
b) x_1<=x_2+x_3+x_4
c)x_2<=x_3+x_4
I have been using the
?ConstrOptim? R-function with the instructions
2006 Jan 12
1
Problem with NLSYSTEMFIT()
Hello,
I want to solve a nonlinear 3SLS problem with "nlsystemfit()". The
equations
are of the form
y_it = f_i(x,t,theta)
The functions f_i(.) have to be formulated as R-functions. When invoking
"nlsystemfit()" I get the error
Error in deriv.formula(eqns[[i]], names(parmnames)) :
Function 'f1' is not in the derivatives table
2004 Aug 31
2
sample size for t-tests
Dear all,
Could any one please tell me the exact formula R uses to calculate the sample size for one-sample and two-sample t-tests? Thanks,
Caimiao
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