R: Save End State to Checkpoint File

mxSave {OpenMx} | R Documentation

## Save End State to Checkpoint File

### Description

The function saves the last state of a model to a checkpoint file.

### Usage

    mxSave(model, chkpt.directory = ".", chkpt.prefix = "")

### Arguments

`model` | MxModel object to be loaded.
`chkpt.directory` | character. Directory where the checkpoint file is located.
`chkpt.prefix` | character. Prefix of the checkpoint file.

### Details

In general, the arguments ‘chkpt.directory’ and ‘chkpt.prefix’ should be identical to the `mxOption`: ‘Checkpoint Directory’ and ‘Checkpoint Prefix’ that were specificed 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`.

### Value

Returns a logical indicating the succes of writing the checkpoint file to the checkpoint directory.

### References

The OpenMx User's guide can be found at http://openmx.ssri.psu.edu/documentation.

### Examples

    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)

    # 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

    # Imagine how much time you saved by not having to re-run the
    # model that took hours or days to run.

[Package OpenMx version 2.9.6 Index]