Displaying 3 results from an estimated 3 matches for "selectedbeta".
2013 Dec 07
1
combine glmnet and coxph (and survfit) with strata()
...ta() effect
in the model in glmnet? I tried converting a formula with strata() to a
design matrix and feeding to glmnet, but glmnet just treats the strata()
term with one independent variable...
I know that if there is no such strata(), I can estimate coefficients from
glmnet and use "...init=selectedBeta,iter=0)" in the coxph. Please advise
me or also correct me if I'm wrong.
Thank you very much!
Best,
Jieyue
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2012 May 07
1
estimating survival times with glmnet and coxph
....5,maxit=10000)
# find lambda for which dev.ratio is max
max.dev.index???? <- which.max(fit$dev.ratio)
optimal.lambda <- fit$lambda[max.dev.index]
# take beta for optimal lambda
optimal.beta? <- fit$beta[,max.dev.index]
# find non zero beta coef
nonzero.coef <- abs(optimal.beta)>0
selectedBeta <- optimal.beta[nonzero.coef]
# take only covariates for which beta is not zero
selectedTrainX?? <- trainX[,nonzero.coef]
# create coxph object with pre-defined coefficients
coxph.model<- coxph(Surv(trainTime,trainStatus) ~selectedTrainX,init=selectedBeta,iter=0)
Warning message:
In cox...
2013 Jul 06
1
problem with BootCV for coxph in pec after feature selection with glmnet (lasso)
....ratio is max 
  max.dev.index <- which.max(glmnet.obj$dev.ratio) 
  optimal.lambda <- glmnet.obj$lambda[max.dev.index] 
  
 
 # take beta for optimal lambda 
  optimal.beta  <- glmnet.obj$beta[,max.dev.index] 
  
  
# find non zero beta coef 
  nonzero.coef <- abs(optimal.beta)>0 
  selectedBeta <- optimal.beta[nonzero.coef] 
  
  # take only covariates for which beta is not zero 
  selectedVar   <- predict_matrix[,nonzero.coef] 
  
  # create a dataframe for trainSet with time, status and selected variables
in binary representation for evaluation in pec
  reformat_dataSet <- as.d...