Displaying 20 results from an estimated 700 matches similar to: "iterative variable names"
2011 Dec 09
2
display memory usage
Does anybody knows how can I display the memory usage in R? I'd like to know
how much RAM R is using to store a data set that I'm reading, is it
possible?
Thanks in advance,
Beatriz
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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
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 =
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)??
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
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
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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
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).
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
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
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:
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
2019 May 16
5
nrow(rbind(character(), character())) returns 2 (as documented but very unintuitive, IMHO)
Hi all,
Apologies if this has been asked before (a quick google didn't find it for
me),and I know this is a case of behaving as documented but its so
unintuitive (to me at least) that I figured I'd bring it up here anyway. I
figure its probably going to not be changed, but I'm happy to submit a
patch if this is something R-core feels can/should change.
So I recently got bitten by
2011 May 22
2
Finding solution set of system of linear equations.
I have a simple system of linear equations to solve for X, aX=b:
> a
[,1] [,2] [,3] [,4]
[1,] 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
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
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 3
in x is still the 1st element in x.sort, 5 is at
2014 Aug 21
2
[LLVMdev] Alias Analysis Semantics
Hi Daniel,
Sorry for taking so long to respond. I spoke with a colleague more
familiar with llvm who thought he could clear up my confusion, but we both
came out of the conversation confused. I will try my best to explain the
ambiguity.
In an DAG, alias queries would be completely unambiguous. Every
instruction would only be executed once, and every SSA value really would
have a single static
2007 Oct 01
3
optimize() stuck in local plateau ?
Hi all,
Consider the following function:
####
my.func = function(x){
y=ifelse(x>-.5,0,ifelse(x< -.8,abs(x)/2,abs(x)))
print(c(x,y)) #print what was tested and what the result is
return(y)
}
curve(my.func,from=-1,1)
####
When I attempt to find the maximum of this function, which should be
-.8, I find that optimize gets stuck in the plateau area and doesn't
bother testing the