The function saves the last state of a model to a checkpoint file.
mxSave(model, chkpt.directory = ".", chkpt.prefix = "")Returns a logical indicating the success of writing the checkpoint file to the checkpoint directory.
an MxModel object
character. Directory where the checkpoint file is located
character. Prefix of the checkpoint file
In general, the arguments ‘chkpt.directory’ and ‘chkpt.prefix’ should be identical to the mxOption: ‘Checkpoint Directory’ and ‘Checkpoint Prefix’ that were specified on the model before execution.
Alternatively, the checkpoint file can be manually loaded as a data.frame in R. Use read.table with the options header=TRUE, sep="\t", stringsAsFactors=FALSE, check.names=FALSE.
The OpenMx User's guide can be found at https://openmx.ssri.psu.edu/documentation
Other model state:
mxComputeCheckpoint(),
mxRestore()
library(OpenMx)
# Simulate some data
x=rnorm(1000, mean=0, sd=1)
y= 0.5*x + rnorm(1000, mean=0, sd=1)
tmpFrame <- data.frame(x, y)
tmpNames <- names(tmpFrame)
dir <- tempdir() # safe place to create files
mxOption(key="Checkpoint Directory", value=dir)
# Create a model that includes an expected covariance matrix,
# an expectation function, a fit function, and an observed covariance matrix
data <- mxData(cov(tmpFrame), type="cov", numObs = 1000)
expCov <- mxMatrix(type="Symm", nrow=2, ncol=2, values=c(.2,.1,.2), free=TRUE, name="expCov")
expFunction <- mxExpectationNormal(covariance="expCov", dimnames=tmpNames)
fitFunction <- mxFitFunctionML()
testModel <- mxModel(model="testModel", expCov, data, expFunction, fitFunction)
#Use mxRun to optimize the free parameters in the expected covariance matrix
modelOut <- mxRun(testModel)
modelOut$expCov
# Save the ending state of modelOut in a checkpoint file
mxSave(modelOut)
# Restore the saved model from the checkpoint file
modelSaved <- mxRestore(testModel)
modelSaved$expCov
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