xmuValues: xmuValues: Set values in RAM model, matrix, or path

In tbates/umx: Structural Equation Modeling and Twin Modeling in R

xmuValues: Set values in RAM model, matrix, or path

Description

For models to be estimated, it is essential that path values start at credible values. xmuValues takes on that task for you.

Usage

xmuValues(obj = NA, sd = NA, n = 1, onlyTouchZeros = FALSE)

Arguments

obj	The RAM or matrix OpenMx::mxModel(), or OpenMx::mxMatrix() that you want to set start values for.
sd	Optional Standard Deviation for start values
n	Optional Mean for start values
onlyTouchZeros	Don't alter parameters that have starts (useful to speed umxModify())

Details

xmuValues can set start values for the free parameters in both RAM and Matrix OpenMx::mxModel()s. It can also take an mxMatrix as input. It tries to be smart in guessing starts from the values in your data and the model type.

note: If you give xmuValues a numeric input, it will use obj as the mean, and return a list of length n, with sd = sd.

Value

• OpenMx::mxModel() with updated start values

References

• https://github.com/tbates/umx, https://tbates.github.io

See Also

• Core functions:

Other Advanced Model Building Functions: umx, umxAlgebra(), umxFixAll(), umxJiggle(), umxRun(), umxThresholdMatrix(), umxUnexplainedCausalNexus(), xmuLabel()

Examples

## Not run: 
require(umx)
data(demoOneFactor)
latents = c("G")
manifests = names(demoOneFactor)

# ====================================================================
# = Make an OpenMx model (which will lack start values and labels..) =
# ====================================================================
m1 = mxModel("One Factor", type = "RAM", 
	manifestVars = manifests, latentVars = latents, 
	mxPath(from = latents  , to = manifests),
	mxPath(from = manifests, arrows = 2),
	mxPath(from = latents  , arrows = 2, free = FALSE, values = 1.0),
	mxData(cov(demoOneFactor), type = "cov", numObs=500)
)
mxEval(S, m1) # default variances are jiggled away from near-zero
# Add start values to the model
m1 = xmuValues(m1)
mxEval(S, m1) # plausible variances
umx_print(mxEval(S,m1), 3, zero.print = ".") # plausible variances
xmuValues(14, sd = 1, n = 10) # Return vector of length 10, with mean 14 and sd 1


## End(Not run)

tbates/umx documentation built on Dec. 14, 2024, 11:28 a.m.