OpenMx Wishlist

Maybe mxRedim(mat, row, col)? Conformance would require that the total number of elements remain constant. That is, mat->rows * mat->cols == row * col.

Semantics would probably fill in by columns.

I'm rather new to the field of SEM, but I am very happy about OpenMx - the learning curve really was really steep (... in the sense of quick successes). Congratulations!

In some post there are already some hints about a "mxCompare" function. I tried to implement a likelihood ratio / chi square test myself:

require(OpenMx)
A <- mxMatrix('Full', 1, 1, values = 1, name = 'A')

Chol    = mxMatrix(type="Full", 2,2, free=c(TRUE,TRUE,FALSE,TRUE), values=c(1,.2,0,1))

But this fails

Chol@free=c(TRUE,FALSE,FALSE,TRUE)
Chol@values=c(1,0,0,1)

It would be nice, given that we can create the free and values slots with vectors, if we could also update them iwth vectors, using the pre-existing nrow and ncol of the MxMatrix to do this:

vec2MatFormxMatrix <- function(oldMat, newVec) {
 newMat = matrix(data=newVec, nrow=nrow(oldMat), ncol=ncol(oldMat) )
 return(newMat)
}

newVec =c(TRUE,FALSE,FALSE,TRUE)

The cleanest way to implement it for the user would be as a parameter to mxRun, where you pass in the last fit, and this has in it the state of the optimiser which mxRun pushes into the current optimiser run as a set of start values.

fit = mxRun(model)
mxRun(model, fit)
#--> returns almost instantly having been started at the optimal location