lasso | R Documentation |
Adaptive LASSO estimation for stochastic differential equations.
lasso(yuima, lambda0, start, delta=1, ...)
yuima |
a yuima object. |
lambda0 |
a named list with penalty for each parameter. |
start |
initial values to be passed to the optimizer. |
delta |
controls the amount of shrinking in the adaptive sequences. |
... |
passed to |
lasso
behaves more likely the standard qmle
function in and
argument method
is one of the methods available in optim
.
From initial guess of QML estimates, performs adaptive LASSO estimation using the Least Squares Approximation (LSA) as in Wang and Leng (2007, JASA).
ans |
a list with both QMLE and LASSO estimates. |
The YUIMA Project Team
## Not run: ##multidimension case diff.matrix <- matrix(c("theta1.1","theta1.2", "1", "1"), 2, 2) drift.c <- c("-theta2.1*x1", "-theta2.2*x2", "-theta2.2", "-theta2.1") drift.matrix <- matrix(drift.c, 2, 2) ymodel <- setModel(drift=drift.matrix, diffusion=diff.matrix, time.variable="t", state.variable=c("x1", "x2"), solve.variable=c("x1", "x2")) n <- 100 ysamp <- setSampling(Terminal=(n)^(1/3), n=n) yuima <- setYuima(model=ymodel, sampling=ysamp) set.seed(123) truep <- list(theta1.1=0.6, theta1.2=0,theta2.1=0.5, theta2.2=0) yuima <- simulate(yuima, xinit=c(1, 1), true.parameter=truep) est <- lasso(yuima, start=list(theta2.1=0.8, theta2.2=0.2, theta1.1=0.7, theta1.2=0.1), lower=list(theta1.1=1e-10,theta1.2=1e-10,theta2.1=.1,theta2.2=1e-10), upper=list(theta1.1=4,theta1.2=4,theta2.1=4,theta2.2=4), method="L-BFGS-B") # TRUE unlist(truep) # QMLE round(est$mle,3) # LASSO round(est$lasso,3) ## End(Not run)
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