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

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: add_lpsolveapi_solver
> ### Title: Add a lp_solve solver with 'lpSolveAPI'
> ### Aliases: add_lpsolveapi_solver
> 
> ### ** Examples
> 
> # load data
> data(sim_projects, sim_features, sim_actions)
> 
> # build problem with lpSolveAPI solver
> p <- problem(sim_projects, sim_actions, sim_features,
+              "name", "success", "name", "cost", "name") %>%
+      add_max_richness_objective(budget = 200) %>%
+      add_binary_decisions() %>%
+      add_lpsolveapi_solver()
> 
> # print problem
> print(p)
Project Prioritization Problem
  actions          F1_action, F2_action, F3_action, ... (6 actions)
  projects         F1_project, F2_project, F3_project, ... (6 projects)
  features         F1, F2, F3, ... (5 features)
  action costs:    min: 0, max: 103.22583
  project success: min: 0.81379, max: 1
  objective:       Maximum richness objective [budget (200)]
  targets:         none
  weights:         default
  decisions        Binary decision 
  constraints:     <none>
  solver:          lpSolveAPI [gap (0), presolve (0), verbose (1)]
> 
> # solve problem
> s <- solve(p)

Model name:  'project prioritization problem' - run #1    
Objective:   Maximize(R0)
 
SUBMITTED
Model size:       47 constraints,      47 variables,          102 non-zeros.
Sets:                                   0 GUB,                  0 SOS.
 
Using DUAL simplex for phase 1 and PRIMAL simplex for phase 2.
The primal and dual simplex pricing strategy set to 'Devex'.
 

Relaxed solution       2.21077983146 after         34 iter is B&B base.
 
Feasible solution      1.91490153549 after         43 iter,         8 nodes (gap 9.2%)
Improved solution       2.0146497578 after         47 iter,        11 nodes (gap 6.1%)
Improved solution      2.19038073724 after         59 iter,        20 nodes (gap 0.6%)
 
Optimal solution       2.19038073724 after         59 iter,        20 nodes (gap 0.6%).

Excellent numeric accuracy ||*|| = 1.11022e-16

 MEMO: lp_solve version 5.5.2.0 for 64 bit OS, with 64 bit LPSREAL variables.
      In the total iteration count 59, 16 (27.1%) were bound flips.
      There were 11 refactorizations, 0 triggered by time and 1 by density.
       ... on average 3.9 major pivots per refactorization.
      The largest [LUSOL v2.2.1.0] fact(B) had 104 NZ entries, 1.0x largest basis.
      The maximum B&B level was 6, 0.1x MIP order, 4 at the optimal solution.
      The constraint matrix inf-norm is 103.226, with a dynamic range of 1193.9.
      Time to load data was 0.076 seconds, presolve used 0.000 seconds,
       ... 0.001 seconds in simplex solver, in total 0.077 seconds.
> 
> # print solution
> print(s)
# A tibble: 1 x 21
  solution status   obj  cost F1_action F2_action F3_action F4_action F5_action
     <int> <chr>  <dbl> <dbl>     <dbl>     <dbl>     <dbl>     <dbl>     <dbl>
1        1 optim…  2.19  195.         1         1         0         0         0
# … with 12 more variables: baseline_action <dbl>, F1_project <dbl>,
#   F2_project <dbl>, F3_project <dbl>, F4_project <dbl>, F5_project <dbl>,
#   baseline_project <dbl>, F1 <dbl>, F2 <dbl>, F3 <dbl>, F4 <dbl>, F5 <dbl>
> 
> # plot solution
> plot(p, s)
Error in grid.Call.graphics(C_setviewport, vp, TRUE) : 
  VECTOR_ELT() can only be applied to a 'list', not a 'double'
Calls: <Anonymous> ... push.vp.vpTree -> push.vp -> push.vp.viewport -> grid.Call.graphics
Execution halted