Displaying 20 results from an estimated 66 matches for "x_2".
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2006 Jun 08
1
panel.abline and xyplot
Dear All,
I am wondering on how to use the abline.xyplot with xyplot such that I will have different vertical lines for each panel. More sepcifically, suppose that the xyplot generates 4 panels defined by the combination of two binary variables: X_1 and X_2. i.e.
xyplot(Y ~ Z | X_1*X_2, data = df)
I want something like:
abline(v = 5) if X_1=0 and X_2 = 0
abline(v = 10) if X_1=0 and X_2 = 1
abline(v = 15) if X_1=1 and X_2 = 0
abline(v = 31) if X_1=1 and X_2 = 1
when I used : xyplot(Y ~ Z | X_1*X_2, data=df, panel = f...
2009 Jun 11
2
Optimization Question
Hi All
Apologies if this is not the correct list for this question.
The Rglpk package offers the following example in its documentation
library(Rglpk)
## Simple mixed integer linear program.
## maximize: 3 x_1 + 1 x_2 + 3 x_3
## subject to: -1 x_1 + 2 x_2 + x_3 <= 4
## 4 x_2 - 3 x_3 <= 2
## x_1 - 3 x_2 + 2 x_3 <= 3
## x_1, x_3 are non-negative integers
## x_2 is a non-negative real number
obj <- c(3, 1, 3)
mat <- matrix(c(-1, 0, 1, 2, 4, -3, 1, -3, 2), nrow = 3)
dir <- c("<=", &quo...
2008 Aug 04
2
Multivariate Regression with Weights
Hi all,
I'd like to fit a multivariate regression with the variance of the error term porportional to the predictors, like the WLS in the univariate case.
y_1~x_1+x_2
y_2~x_1+x_2
var(y_1)=x_1*sigma_1^2
var(y_2)=x_2*sigma_2^2
cov(y_1,y_2)=sqrt(x_1*x_2)*sigma_12^2
How can I specify this in R? Is there a corresponding function to the univariate specification lm(y~x,weights=x)?? Thanks.
Sincerely,
Yanwei Zhang
Department of Actuarial Research and Modeling...
2003 Feb 19
4
fitting a curve according to a custom loss function
Dear R-Users,
I need to find a smooth function f() and coefficients a_i that give the best
fit to
y ~ a_0 + a_1*f(x_1) + a_2*f(x_2)
Note that it is the same non-linear transformation f() that is applied to
both x_1 and x_2.
So my first question is how can I do it in R?
A more general question is this: suppose I have a utility function U(a_i,
f()), where f() is say a spline. Is there a general optimizer that could
find an ex...
2009 Dec 04
2
Solve linear program without objective function
Dear R-users,
i try to solve to following linear programm in R
0 * x_1 + 2/3 * x_2 + 1/3 * x_3 + 1/3 * x_4 = 0.3
x_1 + x_2 + x_3 + x_4 = 1
x_1, x_2, x_3, x_4 > 0,
x_1, x_2, x_3, x_4 < 1
as you can see i have no objective function here besides that i use the
following code.
library(lpSolve)
f.obj<-c(1,1,1,1)
f.con<-matrix(c(0,2/3,1/3,1/3,
1,1,1,1,...
2007 Mar 29
3
Tail area of sum of Chi-square variables
Dear R experts,
I was wondering if there are any R functions that give the tail area
of a sum of chisquare distributions of the type:
a_1 X_1 + a_2 X_2
where a_1 and a_2 are constants and X_1 and X_2 are independent chi-square variables with different degrees of freedom.
Thanks,
Klaus
--
"Feel free" - 5 GB Mailbox, 50 FreeSMS/Monat ...
2009 Oct 01
1
Help for 3D Plotting Data on 'Irregular' Grid
Dear All,
Here is what I am trying to achieve: I would like to plot some data in 3D.
Usually, one has a matrix of the kind
y_1(x_1) , y_1(x_2).....y_1(x_i)
y_2(x_1) , y_2(x_2).....y_2(x_i)
...........................................
y_n(x_1) , y_n(x_2)......y_n(x_i)
where e.g. y_2(x_1) is the value of y at time 2 at point x_1 (see that
the grid in x is the same for the y values at all times).
Instead, in my case, the quantity y is obs...
2004 May 21
2
Help with Plotting Function
Dear List:
I cannot seem to find a way to plot my data correctly. I have a small data frame with 6 total variables (x_1 ... x_6).
I am trying to plot x_1 against x_2 and x_3.
I have tried
plot(x_2, x_1) #obviously works fine
plot(x_3, x_1, add=TRUE) # Does not work. I keep getting error messages.
I would also like to add ablines to this plot.
I have experimented with a number of other plotting functions and I cannot seem to get this to work.
The data are...
2013 Mar 05
2
Issues when using interaction term with a lagged variable
Hi there!
Today I tried to estimate models using both plm and pgmm functions, with an
interaction between X1 and lag(X2, 1). And I notice two issues.
Let "Y=b_1 * X_1 + b_2 * X_2 + b_3 * X_1 * x_2 + e" be our model.
1) When using plm, I got different results when I coded the interaction
term with I(X1 * lag(X2, 1)) and when I just saved this multiplication X1 *
lag(X2, 1) in a different variable of the dataset and then used it. in the
regression.
2) With pgmm it is n...
2012 Sep 20
1
Gummy Variable : Doubt
Hi,
I have a system in which I analyze 2 subjects and 1 variable, so I have
2 models as follow:
y ~ x_1[, 1] + x_2[, 1] + x_1[, 2] + x_2[, 2]
Where
x_1[, i] = cos(2 * pi * t / T_i)
x_2[, i] = sin(2 * pi * t / T_i)
i = 1, 2
Data have two columns: t and y.
As you can see, I have a multiple components model, with rithm and
without trends, and I have a fundamental period (T_1 = 24 hour; T_2 =...
2011 May 22
2
Finding solution set of system of linear equations.
...1 2 1 1
[2,] 3 0 0 4
[3,] 1 -4 -2 -2
[4,] 0 0 0 0
> b
[,1]
[1,] 0
[2,] 2
[3,] 2
[4,] 0
(This is ex Ch1, 2.2 of Artin, Algebra).
So, 3 eqs in 4 unknowns. One can easily use row-reductions to find a
homogeneous solution(b=0) of:
X_1 = 0, X_2 = -c/2, X_3 = c, X_4 = 0
and solutions of the above system are:
X_1 = 2/3, X_2 = -1/3-c/2, X_3 = c, X_4 = 0.
So the Kernel is 1-D spanned by X_2 = -X_3 /2, (nulliity=1), rank is 3.
In R I use solve():
> solve(a,b)
Error in solve.default(a, b) :
Lapack routine dgesv: system is exactly sin...
2007 Feb 02
1
multinomial logistic regression with equality constraints?
I'm interested in doing multinomial logistic regression with equality
constraints on some of the parameter values. For example, with
categorical outcomes Y_1 (baseline), Y_2, and Y_3, and covariates X_1
and X_2, I might want to impose the equality constraint that
\beta_{2,1} = \beta_{3,2}
that is, that the effect of X_1 on the logit of Y_2 is the same as the
effect of X_2 on the logit of Y_3.
Is there an existing facility or package in R for doing this? Would
multinomRob fit the bill?
Many thank...
2012 Sep 05
2
Improvement of Regression Model
Hello folks,
I am on learning phase of R. I have developed Regression Model over six
predictor variables. while development, i found my all data are not very
linear. So, may because of this the prediction of my model is not exact.
Here is the summary of model :
Call:
lm(formula = y ~ x_1 + x_2 + x_3 + x_4 + x_5 + x_6)
Residuals:
Min 1Q Median 3Q Max
-125.302 -26.210 0.702 26.261 111.511
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 48.62944 0.27999 173.684 < 2e-16 ***
x_1 -0.67831 0.08053 -8.423 < 2e-...
2019 May 16
0
nrow(rbind(character(), character())) returns 2 (as documented but very unintuitive, IMHO)
The existing behaviour seems inutitive to me. I would consider these
invariants for n vector x_i's each with size m:
* nrow(rbind(x_1, x_2, ..., x_n)) equals n
* ncol(rbind(x_1, x_2, ..., x_n)) equals m
Additionally, wouldn't you expect rbind(x_1[i], x_2[i]) to equal
rbind(x_1, x_2)[, i, drop = FALSE] ?
Hadley
On Thu, May 16, 2019 at 3:26 PM Gabriel Becker <gabembecker at gmail.com> wrote:
>
> Hi all,
>
> Apol...
2014 Aug 21
2
[LLVMdev] Alias Analysis Semantics
...> }
> >
>
> This is not what it looks like in LLVM.
>
> In LLVM, it looks like this:
>
> std::vector<int> A(100);
>> int* x,y;
>>
>
>>
> x_1=GEP A, 0, 0
>>
> for(int i=0; i<100; i++) {
>>
> i_2 = phi (0, i_3)
> x_2 = phi(x_1, x_3)
> y_1 = GEP A, 0, i_2
> temp = load x_2
> store y_1, temp
> temp2 = add i_2, 1
> x_3 = GEP A, 0, temp2
> i_3 = add i_2, 1
> }
>
> As you can see, every time you redefine the value of the pointer x to a
> new value, it gets a new...
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 I report below, and I
have tried to implement them with different values of ?n?. BUT I have
encountered 2 problems:
1) the result of the maximization is the same
of the minimization, i.e. the maximum...
2000 Oct 03
5
Where is gam?
I noticed that there is no generalised additive model functions in R
(1.1.1) ... is there a package that implements them?
Thanks
Prasad
*****************************************************************
Mr. Anantha Prasad, Ecologist/GIS Specialist
USDA Forest Service, 359 Main Rd.
Delaware OHIO 43015 USA
Ph: 740-368-0103 Email: aprasad at fs.fed.us
Web:
2014 Aug 14
2
[LLVMdev] Alias Analysis Semantics
On Thu, Aug 14, 2014 at 6:37 AM, Daniel Berlin <dberlin at dberlin.org> wrote:
> On Wed, Aug 13, 2014 at 8:35 PM, Jeremy Salwen <jeremysalwen at gmail.com> wrote:
>> Hey Daniel,
>>
>> Thanks again for the help. I'm still a bit confused about the interface to
>> the alias analysis. It seems like we are talking about different
>> interfaces.
>
2013 Mar 11
3
How to obtain the original indices of elements after sorting
Dear All,
Suppose I have a vector X = (x_1, x_2, ...., x_n), X_sort = sort(X)
= (x_(1), x_(2), ... , x(n) ),
and I would like to know the original position of these ordered x_(i)
in X, how can I do it?
case 1: all values are unique
x <- c( 3, 5, 4, 6)
x.sort <- sort(x) #
# I would like to obtain a vector (1, 3, 2, 4) which indicates that...
2017 Jun 11
1
Memory leak in nleqslv()
...I am having issues with iterations over nleqslv, in that the solver
does not appear to clean up memory used in previous iterations. I
believe I've isolated the/my issue in a small sample of code:
library(nleqslv)
cons_ext_test <- function(x){
rows_x <- length(x)/2
x_1 <- x[1:rows_x]
x_2 <- x[(rows_x+1):(rows_x*2)]
eq1<- x_1-100
eq2<-x_2*10-40
return(c(eq1,eq2))
}
model_test <- function()
{
reserves<-(c(0:200)/200)^(2)*2000
lambda <- numeric(NROW(reserves))+5
res_ext <- pmin((reserves*.5),5)
x_test <- c(res_ext,lambda)
#print(x_test)
for(test_iter in c(1:10...