Running examples in ‘gWQS-Ex.R’ failed
The error most likely occurred in:

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: gwqs
> ### Title: Fitting Weighted Quantile Sum regression models
> ### Aliases: gwqs
> 
> ### ** Examples
> 
> # we save the names of the mixture variables in the variable "toxic_chems"
> toxic_chems = c("log_LBX074LA", "log_LBX099LA", "log_LBX105LA", "log_LBX118LA",
+ "log_LBX138LA", "log_LBX153LA", "log_LBX156LA", "log_LBX157LA", "log_LBX167LA",
+ "log_LBX170LA", "log_LBX180LA", "log_LBX187LA", "log_LBX189LA", "log_LBX194LA",
+ "log_LBX196LA", "log_LBX199LA", "log_LBXD01LA", "log_LBXD02LA", "log_LBXD03LA",
+ "log_LBXD04LA", "log_LBXD05LA", "log_LBXD07LA", "log_LBXF01LA", "log_LBXF02LA",
+ "log_LBXF03LA", "log_LBXF04LA", "log_LBXF05LA", "log_LBXF06LA", "log_LBXF07LA",
+ "log_LBXF08LA", "log_LBXF09LA", "log_LBXPCBLA", "log_LBXTCDLA", "log_LBXHXCLA")
> 
> # To run a linear model and save the results in the variable "results". This linear model
> # (family="Gaussian") will rank/standardize variables in quartiles (q = 4), perform a
> # 40/60 split of the data for training/validation (validation = 0.6), and estimate weights
> # over 5 bootstrap samples (b = 3). Weights will be derived from mixture effect
> # parameters that are positive (b1_pos = TRUE). A unique seed was specified (seed = 2016) so
> # this model will be reproducible, and plots describing the variable weights and linear
> # relationship will be generated as output (plots = TRUE). In the end tables describing the
> # weights values and the model parameters with the respectively statistics are generated in
> # the viewer window
> results = gwqs(y ~ NULL, mix_name = toxic_chems, data = wqs_data, q = 4, validation = 0.6,
+                b = 3, b1_pos = TRUE, b1_constr = FALSE, family = "gaussian", seed = 2016,
+                wqs2 = FALSE, plots = TRUE, tables = TRUE)
[1] "The optimization function did not converge 0 times"
Error in grid.Call.graphics(C_setviewport, vp, TRUE) : 
  VECTOR_ELT() can only be applied to a 'list', not a 'double'
Calls: gwqs ... lapply -> FUN -> push.vp.viewport -> grid.Call.graphics
Execution halted