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#
# Copyright 2007-2019 by the individuals mentioned in the source code history
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#preamble of some kind
library(OpenMx)
#sample size
n <- 500
set.seed(10)
# generate data
x <- rnorm(n, 3, 2)
z <- rep(1:4, each=n/4)
y <- (.8^z) * x + rnorm(n)
data <- data.frame(x,y,z)
model <- mxModel("Non Linear Definition",
mxData(data, "raw"),
mxMatrix("Diag", 2, 2, T, 1, name="S"),
mxMatrix("Full", 2, 2,
free=c(F, F, F, F),
values=c(1, 0, 0, 1),
labels=c(NA, "bexp[1,1]", NA, NA),
name="IA"),
mxMatrix("Full", 1, 1, T, 0.7, "beta1", name="B"),
mxMatrix("Full", 1, 1, F, 0, "data.z", name="D"),
mxMatrix("Full", 1, 2, T, 0, c("mu_x", "beta0"), name="M"),
mxAlgebra(B ^ D, name="bexp"),
mxAlgebra(M %*% t(IA), name="mu"),
mxAlgebra(IA %*% S %*% t(IA), name="sigma"),
mxExpectationNormal("sigma", "mu", dimnames=c("x", "y")),
mxFitFunctionML()
)
results <- mxRun(model)
summary(results)
check <- nls(y ~ b0 + (b1 ^ z) * x, start=list(b0=0, b1=0.7))
#beta0
omxCheckCloseEnough(results$output$estimate[5],
summary(check)$parameters[1], 0.01)
#beta1
omxCheckCloseEnough(results$output$estimate[3],
summary(check)$parameters[2], 0.01)
# -----------------
data$z <- mxFactor(z, levels=1:4, labels=c("a",'b','c','d'))
model <- mxModel(model, mxData(data, "raw"))
result <- omxCheckWarning(mxRun(model),
"Non Linear Definition.data: definition variable 'z' is of type 'ordered factor'; note that it will be treated as integer (as is done by ?unclass). Is this really what you want to do? Really?")
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