Examples

library(rPBK)

Single Compartment and Single Exposure : Male Gammarus Single

data("dataMaleGammarusSingle")
# work only when replicate have the same length !!!
data_MGS <- dataMaleGammarusSingle[dataMaleGammarusSingle$replicate == 1,]
modelData_MGS <- dataPBK(
  object = data_MGS,
  col_time = "time",
  col_replicate = "replicate",
  col_exposure = "expw",
  col_compartment = "conc",
  time_accumulation = 4,
  nested_model = NA)
fitPBK_MGS <- fitPBK(modelData_MGS)
#> 
#> SAMPLING FOR MODEL 'PBK_AD' NOW (CHAIN 1).
#> Chain 1: 
#> Chain 1: Gradient evaluation took 5.2e-05 seconds
#> Chain 1: 1000 transitions using 10 leapfrog steps per transition would take 0.52 seconds.
#> Chain 1: Adjust your expectations accordingly!
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#> Chain 1:                0.737 seconds (Total)
#> Chain 1: 
#> 
#> SAMPLING FOR MODEL 'PBK_AD' NOW (CHAIN 2).
#> Chain 2: 
#> Chain 2: Gradient evaluation took 3.6e-05 seconds
#> Chain 2: 1000 transitions using 10 leapfrog steps per transition would take 0.36 seconds.
#> Chain 2: Adjust your expectations accordingly!
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#> Chain 2:  Elapsed Time: 0.58 seconds (Warm-up)
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#> Chain 2:                0.8 seconds (Total)
#> Chain 2: 
#> 
#> SAMPLING FOR MODEL 'PBK_AD' NOW (CHAIN 3).
#> Chain 3: 
#> Chain 3: Gradient evaluation took 4.7e-05 seconds
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#> Chain 3:  Elapsed Time: 0.549 seconds (Warm-up)
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#> Chain 3:                1.199 seconds (Total)
#> Chain 3: 
#> 
#> SAMPLING FOR MODEL 'PBK_AD' NOW (CHAIN 4).
#> Chain 4: 
#> Chain 4: Gradient evaluation took 4.9e-05 seconds
#> Chain 4: 1000 transitions using 10 leapfrog steps per transition would take 0.49 seconds.
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#> Chain 4: 
#> Chain 4:  Elapsed Time: 0.405 seconds (Warm-up)
#> Chain 4:                0.336 seconds (Sampling)
#> Chain 4:                0.741 seconds (Total)
#> Chain 4:
#> Warning: There were 2227 divergent transitions after warmup. See
#> https://mc-stan.org/misc/warnings.html#divergent-transitions-after-warmup
#> to find out why this is a problem and how to eliminate them.
#> Warning: Examine the pairs() plot to diagnose sampling problems
#> Warning: Bulk Effective Samples Size (ESS) is too low, indicating posterior means and medians may be unreliable.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#bulk-ess
#> Warning: Tail Effective Samples Size (ESS) is too low, indicating posterior variances and tail quantiles may be unreliable.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#tail-ess
plot(fitPBK_MGS)

library(loo)
#> This is loo version 2.6.0
#> - Online documentation and vignettes at mc-stan.org/loo
#> - As of v2.0.0 loo defaults to 1 core but we recommend using as many as possible. Use the 'cores' argument or set options(mc.cores = NUM_CORES) for an entire session.
log_lik_MGS <- loo::extract_log_lik(fitPBK_MGS$stanfit, merge_chains = FALSE)
WAIC_MGS <- waic(log_lik_MGS)
#> Warning: 
#> 1 (12.5%) p_waic estimates greater than 0.4. We recommend trying loo instead.

Multiple Compartiment, Single Exposure - Default interaction

data("dataCompartment4")
data_C4 <- dataCompartment4
modelData_C4 <- dataPBK(
  object = data_C4,
  col_time = "temps",
  col_replicate = "replicat",
  col_exposure = "condition",
  col_compartment = c("intestin", "reste", "caecum", "cephalon"),
  time_accumulation = 7)

You can have a look at the assumption on the interaction

nested_model(modelData_C4)
#> $ku_nest
#> uptake intestin    uptake reste   uptake caecum uptake cephalon 
#>               1               1               1               1 
#> 
#> $ke_nest
#> excretion intestin    excretion reste   excretion caecum excretion cephalon 
#>                  1                  1                  1                  1 
#> 
#> $k_nest
#>          intestin reste caecum cephalon
#> intestin        0     1      1        1
#> reste           1     0      1        1
#> caecum          1     1      0        1
#> cephalon        1     1      1        0
fitPBK_C4 <- fitPBK(modelData_C4, chains = 1, iter = 1000)
#> 
#> SAMPLING FOR MODEL 'PBK_AD' NOW (CHAIN 1).
#> Chain 1: 
#> Chain 1: Gradient evaluation took 0.000897 seconds
#> Chain 1: 1000 transitions using 10 leapfrog steps per transition would take 8.97 seconds.
#> Chain 1: Adjust your expectations accordingly!
#> Chain 1: 
#> Chain 1: 
#> Chain 1: Iteration:   1 / 1000 [  0%]  (Warmup)
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#> Chain 1: 
#> Chain 1:  Elapsed Time: 20.905 seconds (Warm-up)
#> Chain 1:                179.312 seconds (Sampling)
#> Chain 1:                200.217 seconds (Total)
#> Chain 1:
#> Warning: There were 432 divergent transitions after warmup. See
#> https://mc-stan.org/misc/warnings.html#divergent-transitions-after-warmup
#> to find out why this is a problem and how to eliminate them.
#> Warning: There were 68 transitions after warmup that exceeded the maximum treedepth. Increase max_treedepth above 10. See
#> https://mc-stan.org/misc/warnings.html#maximum-treedepth-exceeded
#> Warning: Examine the pairs() plot to diagnose sampling problems
#> Warning: The largest R-hat is NA, indicating chains have not mixed.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#r-hat
#> Warning: Bulk Effective Samples Size (ESS) is too low, indicating posterior means and medians may be unreliable.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#bulk-ess
#> Warning: Tail Effective Samples Size (ESS) is too low, indicating posterior variances and tail quantiles may be unreliable.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#tail-ess
plot(fitPBK_C4)

Compute WAIC with loo library:

library(loo)
log_lik_C4 <- loo::extract_log_lik(fitPBK_C4$stanfit, merge_chains = FALSE)
WAIC_C4 <- waic(log_lik_C4)
#> Warning: 
#> 6 (7.1%) p_waic estimates greater than 0.4. We recommend trying loo instead.
print(WAIC_C4)
#> 
#> Computed from 500 by 84 log-likelihood matrix
#> 
#>           Estimate   SE
#> elpd_waic   -255.5 18.0
#> p_waic        10.6  1.7
#> waic         511.0 36.0
#> 
#> 6 (7.1%) p_waic estimates greater than 0.4. We recommend trying loo instead.

Compute LOO:

r_eff_C4 <- relative_eff(exp(log_lik_C4))
LOO_C4 <- loo(log_lik_C4, r_eff = r_eff_C4, cores = 2)
print(LOO_C4)
#> 
#> Computed from 500 by 84 log-likelihood matrix
#> 
#>          Estimate   SE
#> elpd_loo   -255.6 18.0
#> p_loo        10.6  1.7
#> looic       511.2 36.0
#> ------
#> Monte Carlo SE of elpd_loo is 0.9.
#> 
#> All Pareto k estimates are good (k < 0.5).
#> See help('pareto-k-diagnostic') for details.

Multiple Compartiment, Single Exposure : Change nesting

You can have a look at the assumption on the interaction

nm_C4 = nested_model(modelData_C4)

We want to change the interaction between organs. For now, all organs interact with each other but not with themselve, the the interaction matrix look like:

nm_C4$k_nest
#>          intestin reste caecum cephalon
#> intestin        0     1      1        1
#> reste           1     0      1        1
#> caecum          1     1      0        1
#> cephalon        1     1      1        0

which can be written like:

matrix(c(
  c(0,1,1,1),
  c(1,0,1,1),
  c(1,1,0,0),
  c(1,1,1,0)),
  ncol=4,nrow=4,byrow=TRUE)
#>      [,1] [,2] [,3] [,4]
#> [1,]    0    1    1    1
#> [2,]    1    0    1    1
#> [3,]    1    1    0    0
#> [4,]    1    1    1    0

Let assume interaction are only one way, so a triangular matrix:

matrix(c(
  c(0,1,1,1),
  c(0,0,1,1),
  c(0,0,0,0),
  c(0,0,0,0)),
  ncol=4,nrow=4,byrow=TRUE)
#>      [,1] [,2] [,3] [,4]
#> [1,]    0    1    1    1
#> [2,]    0    0    1    1
#> [3,]    0    0    0    0
#> [4,]    0    0    0    0
modelData_C42 <- dataPBK(
  object = data_C4,
  col_time = "temps",
  col_replicate = "replicat",
  col_exposure = "condition",
  col_compartment = c("intestin", "reste", "caecum", "cephalon"),
  time_accumulation = 7,
  ku_nest = c(1,1,1,1), # No Change here
  ke_nest = c(1,1,1,1), # No Change here
  k_nest = matrix(c(
            c(0,1,1,1),
            c(0,0,1,1),
            c(0,0,0,0),
            c(0,0,0,0)),
            ncol=4,nrow=4,byrow=TRUE) # Remove 
  )
nested_model(modelData_C42)
#> $ku_nest
#> uptake intestin    uptake reste   uptake caecum uptake cephalon 
#>               1               1               1               1 
#> 
#> $ke_nest
#> excretion intestin    excretion reste   excretion caecum excretion cephalon 
#>                  1                  1                  1                  1 
#> 
#> $k_nest
#>          intestin reste caecum cephalon
#> intestin        0     1      1        1
#> reste           0     0      1        1
#> caecum          0     0      0        0
#> cephalon        0     0      0        0
fitPBK_C42 <- fitPBK(modelData_C42, chains = 1, iter = 1000)
#> 
#> SAMPLING FOR MODEL 'PBK_AD' NOW (CHAIN 1).
#> Chain 1: 
#> Chain 1: Gradient evaluation took 0.000756 seconds
#> Chain 1: 1000 transitions using 10 leapfrog steps per transition would take 7.56 seconds.
#> Chain 1: Adjust your expectations accordingly!
#> Chain 1: 
#> Chain 1: 
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#> Chain 1: Iteration: 1000 / 1000 [100%]  (Sampling)
#> Chain 1: 
#> Chain 1:  Elapsed Time: 9.878 seconds (Warm-up)
#> Chain 1:                10.872 seconds (Sampling)
#> Chain 1:                20.75 seconds (Total)
#> Chain 1:
#> Warning: There were 500 divergent transitions after warmup. See
#> https://mc-stan.org/misc/warnings.html#divergent-transitions-after-warmup
#> to find out why this is a problem and how to eliminate them.
#> Warning: Examine the pairs() plot to diagnose sampling problems
#> Warning: The largest R-hat is NA, indicating chains have not mixed.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#r-hat
#> Warning: Bulk Effective Samples Size (ESS) is too low, indicating posterior means and medians may be unreliable.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#bulk-ess
#> Warning: Tail Effective Samples Size (ESS) is too low, indicating posterior variances and tail quantiles may be unreliable.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#tail-ess
plot(fitPBK_C42)

log_lik_C42 <- loo::extract_log_lik(fitPBK_C42$stanfit, merge_chains = FALSE)
WAIC_C42 <- waic(log_lik_C42)
#> Warning: 
#> 3 (3.6%) p_waic estimates greater than 0.4. We recommend trying loo instead.
print(WAIC_C42)
#> 
#> Computed from 500 by 84 log-likelihood matrix
#> 
#>           Estimate   SE
#> elpd_waic   -279.8 14.3
#> p_waic         6.5  1.4
#> waic         559.7 28.6
#> 
#> 3 (3.6%) p_waic estimates greater than 0.4. We recommend trying loo instead.

Compare WAIC with previous model

comp_C4_C42 <- loo_compare(WAIC_C4, WAIC_C42)
print(comp_C4_C42)
#>        elpd_diff se_diff
#> model1   0.0       0.0  
#> model2 -24.3      10.2

The first column shows the difference in ELPD relative to the model with the largest ELPD. In this case, the difference in elpd and its scale relative to the approximate standard error of the difference) indicates a preference for the second model (model2).