Running examples in 'isotracer-Ex.R' failed
The error most likely occurred in:

> ### Name: add_covariates
> ### Title: Add fixed effects of one or several covariates to some
> ###   parameters.
> ### Aliases: add_covariates
> 
> ### ** Examples
> 
> # Using a subset of the topology from the Trinidad case study
> m <- new_networkModel() %>%
+   set_topo("NH4, NO3 -> epi, FBOM", "epi -> petro, pseph")
Using default distribution family for proportions ("gamma_cv").
  (eta is the coefficient of variation of gamma distributions.)
Using default distribution family for sizes ("normal_cv").
  (zeta is the coefficient of variation of normal distributions.)
> 
> # Taking initial condtions from the 'lalaja' dataset at t=0
> # Grouping by transect id
> inits <- lalaja[lalaja[["time.days"]] == 0, ]
> inits
# A tibble: 24 x 6
# Groups:   stream, transect [3]
   stream transect   compartment mgN.per.m2 prop15N time.days
   <chr>  <chr>      <chr>            <dbl>   <dbl>     <dbl>
 1 UL     transect.1 NH4              0.300 0.0240          0
 2 UL     transect.1 NO3             31.5   0.00397         0
 3 UL     transect.2 NH4              0.300 0.0140          0
 4 UL     transect.2 NO3             31.5   0.00407         0
 5 UL     transect.3 NH4              0.300 0.00694         0
 6 UL     transect.3 NO3             31.5   0.00413         0
 7 UL     transect.1 arg              2.31  0.00366         0
 8 UL     transect.2 arg              2.31  0.00366         0
 9 UL     transect.3 arg              2.31  0.00366         0
10 UL     transect.1 epi            329.    0.00366         0
# ... with 14 more rows
> m <- set_init(m, inits, comp = "compartment", size = "mgN.per.m2",
+               prop = "prop15N", group_by = "transect")
Some compartments are not present in the network topology and are
removed from the initial data:
  - arg
  - tricor

> m
# A tibble: 3 x 5
  topology           initial          observations parameters        group    
  <list>             <list>           <list>       <list>            <list>   
1 <topology [6 x 6]> <tibble [6 x 3]> <NULL>       <tibble [14 x 2]> <chr [1]>
2 <topology [6 x 6]> <tibble [6 x 3]> <NULL>       <tibble [14 x 2]> <chr [1]>
3 <topology [6 x 6]> <tibble [6 x 3]> <NULL>       <tibble [14 x 2]> <chr [1]>
> 
> # Default model
> params(m, simplify = TRUE)
 [1] "eta"                  "lambda_FBOM"          "lambda_NH4"          
 [4] "lambda_NO3"           "lambda_epi"           "lambda_petro"        
 [7] "lambda_pseph"         "upsilon_NH4_to_FBOM"  "upsilon_NH4_to_epi"  
[10] "upsilon_NO3_to_FBOM"  "upsilon_NO3_to_epi"   "upsilon_epi_to_petro"
[13] "upsilon_epi_to_pseph" "zeta"                
> 
> # Adding an effect of the "transect" covariate on some parameters
> m <- add_covariates(m, upsilon_epi_to_pseph ~ transect)
Error in library.dynam(lib, package, package.lib) : 
  DLL 'purrr' not found: maybe not installed for this architecture?
Calls: add_covariates ... groups.networkModel -> nm_get_groups -> loadNamespace -> library.dynam
Execution halted