Last updated: 2021-11-24

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Rmd be89c8d Bernard 2021-11-24 new codes

Load packages

# Import packages --------------------------------------------------------------

# Helper
library(tidyverse)
library(data.table)
library (cowplot)
library (officer)
library (flextable)

# ML
library(mlr3)
library(mlr3learners)
library(mlr3tuning)
library(mlr3viz)
library(mlr3fselect)
library(mlr3pipelines)
library(mlr3hyperband)
library(iml)
library(MASS)
library(MLmetrics)

# Parallel
library (future)

Import data and set tasks

# Import data ------------------------------------------------------------------
dat <- readRDS("output/df.RDS")

np_dat <- bind_rows(dat$df_list$np$train_imp, dat$df_list$np$test_imp) #%>% group_by(outcome) %>% sample_n(50)
ap_dat <- bind_rows(dat$df_list$ap$train_imp, dat$df_list$ap$test_imp) #%>% group_by(outcome) %>% sample_n(50)
dis_dat <- bind_rows(dat$df_list$dis$train_imp, dat$df_list$dis$test_imp) #%>% group_by(outcome) %>% sample_n(50)

# Set ML task ------------------------------------------------------------------

task_np <- TaskClassif$new (id = "neckpain", backend = np_dat , target = "outcome")
task_np$nrow
task_np$feature_names
task_np$set_col_roles("ID", roles = "name")

task_ap <- TaskClassif$new (id = "armpain", backend = ap_dat , target = "outcome")
task_ap$nrow
task_ap$feature_names
task_ap$set_col_roles("ID", roles = "name")

task_dis <- TaskClassif$new (id = "disability", backend = dis_dat , target = "outcome")
task_dis$nrow
task_dis$feature_names
task_dis$set_col_roles("ID", roles = "name")

# Set preprocessing pipes-------------------------------------------------------

poe <- po("encode", method = "one-hot")
poscale <- po("scale", param_vals = list (center = TRUE, scale = TRUE))

# Set generic params------------------------------------------------------------
create_at = function(pipe_lrn, param_set){
  auto_tuner(
    method = "random_search",
    learner = GraphLearner$new(pipe_lrn, task_type = "classif"),
    resampling = rsmp("cv", folds = 3),
    measure = msr("classif.auc"),
    search_space = param_set,
    term_evals = 2000
  )
}

Define ML models

# Define ML models -------------------------------------------------------------
######################### Logistic regression ##################################

lrn_logreg <- lrn("classif.log_reg", id = "log", predict_type = "prob")

grln_logreg <- poscale %>>%
  lrn_logreg

logreg_gl = GraphLearner$new(grln_logreg, task_type = "classif")

######################### KNN ##################################################

lrn_kknn <- lrn("classif.kknn", id = "kknn", predict_type = "prob")

grln_kknn <- poscale %>>%
  poe %>>%
  lrn_kknn

ps_knn <- ParamSet$new(
  params = list(
    ParamInt$new("kknn.k", lower = 1, upper = 10))
  )

kknn_at = create_at(grln_kknn, ps_knn)

######################### Xgboost ##############################################

lrn_xgb <- lrn("classif.xgboost", id = "xgb", predict_type = "prob",  eta = 0.01)

grln_xgb <- poscale %>>%
  poe %>>%
  lrn_xgb

ps_xgb = ParamSet$new(
 params = list(
   ParamDbl$new("xgb.eta", lower = 0.001, upper = 0.2),
   ParamDbl$new("xgb.max_depth", lower = 1, upper = 10),
   ParamDbl$new("xgb.nrounds", lower = 50, upper = 500, tags = "budget"),
   ParamDbl$new("xgb.colsample_bytree", lower = 0.5, upper = 1),
   ParamDbl$new("xgb.colsample_bylevel", lower = 0.5, upper = 1),
   ParamDbl$new("xgb.subsample", lower = 0.5, upper = 1),
   ParamDbl$new("xgb.gamma", lower = -7, upper = 6),
   ParamDbl$new("xgb.lambda", lower = -10, upper = 10),
   ParamDbl$new("xgb.alpha", lower = -10, upper = 10)
))

ps_xgb$trafo = function(x, param_set) {
 idx_gamma = grep("gamma", names(x))
 x[[idx_gamma]] = 2^(x[[idx_gamma]])

 idx_lambda = grep("lambda", names(x))
 x[[idx_lambda]] = as.integer (2^(x[[idx_lambda]]))

 idx_alpha = grep("alpha", names(x))
 x[[idx_alpha]] = as.integer (2^(x[[idx_alpha]]))

 idx_nrounds = grep("nrounds", names(x))
 x[[idx_nrounds]] = as.integer (x[[idx_nrounds]])

 idx_depth = grep("depth", names(x))
 x[[idx_depth]] = as.integer (x[[idx_depth]])

 x
}

xgb_at = create_at(grln_xgb, ps_xgb)

######################### Lasso ################################################

lrn_lasso <- lrn("classif.glmnet", id = "lasso", predict_type = "prob")

grln_lasso <- poscale %>>%
  poe %>>%
  lrn_lasso

ps_lasso =  ParamSet$new(
  params = list(ParamDbl$new("lasso.s", lower = 0, upper = 1))
  )


lasso_at = create_at(grln_lasso, ps_lasso)

######################### Random forest ########################################

lrn_rf <- lrn("classif.ranger", id = "rf", predict_type = "prob")

grln_rf  <- poscale %>>%
  poe %>>%
  lrn_rf

ps_rf <- ParamSet$new(list(
 ParamInt$new ("rf.mtry", lower = 5, upper = 15, tags = "budget"),
 ParamDbl$new ("rf.sample.fraction", lower = 0.5, upper = 1),
 ParamInt$new ("rf.min.node.size", lower = 1, upper = 20)
))

rf_at = create_at(grln_rf, ps_rf)

######################### Nnet #################################################

lrn_net <- lrn("classif.nnet", id = "nnet", predict_type = "prob")

grln_net <- poscale %>>%
  poe %>>%
  lrn_net

ps_nnet <- ParamSet$new(list (
 ParamInt$new ("nnet.size", lower = 1, upper = 10),
 ParamDbl$new ("nnet.decay", lower = 0.1, upper = 0.5)
))

nnet_at = create_at(grln_net, ps_nnet)

######################### SVM ##################################################

lrn_svm <- lrn("classif.svm", id = "svm", type = "C-classification",
               kernel = "radial", predict_type = "prob")

grln_svm <- poscale %>>%
  poe %>>%
  lrn_svm

ps_svm <- ParamSet$new(list (
 ParamDbl$new ("svm.cost", lower = 0.1, upper = 10),
 ParamDbl$new ("svm.gamma", lower = 0, upper = 5)
))

svm_at = create_at(grln_svm, ps_svm)


# Compare against stepwise model -----------------------------------------------

split_fit_predict <- function(data_index)
{

  # recover splits
  index <- bmr$resamplings$resampling[[data_index]]$instance

  # define data
  dat <- list(np_dat, ap_dat, dis_dat)[[data_index]]
  dat_train <- dat[index$train,]
  dat_test <- dat[index$test,]
  # train models
  mod_base <- glm(outcome ~ 1 + ., family = binomial(), data = dat_train[,-1])
  mod_step <- stepAIC(mod_base)
  best_model <- mod_step$formula

  best_fitted <- mod_step$fitted.values
  best_pred <- predict(mod_step, dat_test, type = "response")

  auc <- MLmetrics::AUC (factor((best_fitted > 0.5) * 1), dat_train$outcome)
  acc <- MLmetrics::Accuracy (factor((best_fitted > 0.5) * 1), dat_train$outcome)
  sens <- MLmetrics::Sensitivity (dat_train$outcome, factor((best_fitted > 0.5) * 1))
  spec <- MLmetrics::Specificity (dat_train$outcome, factor((best_fitted > 0.5) * 1))
  prec <- MLmetrics::Precision (dat_train$outcome, factor((best_fitted > 0.5) * 1))
  fbeta <- MLmetrics::FBeta_Score (dat_train$outcome, factor((best_fitted > 0.5) * 1))

  metrics_train <- data.frame (
    auc = auc,
    acc = acc,
    sens = sens,
    spec = spec,
    fbeta = fbeta
  )


  auc <- MLmetrics::AUC (factor((best_pred > 0.5) * 1), dat_test$outcome)
  acc <- MLmetrics::Accuracy (factor((best_pred > 0.5) * 1), dat_test$outcome)
  sens <- MLmetrics::Sensitivity (dat_test$outcome, factor((best_pred > 0.5) * 1))
  spec <- MLmetrics::Specificity (dat_test$outcome, factor((best_pred > 0.5) * 1))
  prec <- MLmetrics::Precision (dat_test$outcome, factor((best_pred > 0.5) * 1))
  fbeta <- MLmetrics::FBeta_Score (dat_test$outcome, factor((best_pred > 0.5) * 1))

  metrics_test <- data.frame (
    auc = auc,
    acc = acc,
    sens = sens,
    spec = spec,
    prec = prec,
    fbeta = fbeta
  )

  return(list(best_model = best_model,
              metrics_train = metrics_train,
              metrics_test = metrics_test))

}

res_step <- lapply(1:3, split_fit_predict)
names(res_step) <- c("np", "ap", "dis")

# extract best models
lapply(res_step, "[[", "best_model")

# extract metrics
lapply(res_step, "[[", "metrics_train")
lapply(res_step, "[[", "metrics_test")

Train models

# Resampling performance -------------------------------------------------------
# See ## See https://mlr3gallery.mlr-org.com/posts/2020-07-27-bikesharing-demand/

## Method 1 - quick benchmarking
### Create benchmark grid

# Ability to do all tasks at once
#
tasks <- list (task_np, task_ap, task_dis)

learners <- list (logreg_gl, kknn_at, xgb_at, lasso_at, rf_at, nnet_at, svm_at)

design <- benchmark_grid(tasks = tasks,
                        learners = learners,
                        resamplings = rsmp("holdout", ratio = 0.8))

set.seed(123456)

plan(multisession, workers = 20L)
bmr <- benchmark(design,
                  store_models = TRUE,
                  store_backends = TRUE)

measures <- list (msr("classif.auc"),
                  msr("classif.acc"),
                  msr("classif.sensitivity"),
                  msr("classif.specificity"),
                  msr("classif.precision"),
                  msr("classif.fbeta"))

resample_perf <- as.data.table (bmr$score(measures = measures)) %>%
  as.data.frame() %>%
  dplyr::select (nr, task_id, learner_id, resampling_id, iteration, matches ("classif."))

Save models

saveRDS(res_step, file="output/stepwise_performance.RDS")

# Save -------------------------------------------------------------------------

saveRDS(resample_perf,
        "output/resample_perf.RDS")

saveRDS(bmr,
        "output/resampling_models.RDS")

Import models

saveRDS(res_step, file="output/stepwise_performance.RDS")

# Save -------------------------------------------------------------------------

saveRDS(resample_perf,
        "output/resample_perf.RDS")

saveRDS(bmr,
        "output/resampling_models.RDS")

# Evaluate results -------------------------------------------------------------

perf <- readRDS("output/resample_perf.RDS")
bmr <- readRDS("output/resampling_models.RDS")
perf_step <- readRDS("output/stepwise_performance.RDS")

Extract results

# Plot performance -------------------------------------------------------------

colz <- c("#030303", "#0000FF", "#EE0000", "#00CD00", "#EE9A00", "#912CEE", "#8B4726")

step_perf <- perf_step %>%
  map ("metrics_test") %>%
  bind_rows(.id = "task_id") %>%
  mutate(task_id = ifelse (task_id == "np", "Neck pain",
                           ifelse (task_id == "ap", "Arm pain", "Disability"))) %>%
  mutate (learner_id = "Stepwise") %>%
  pivot_longer(cols = -c(task_id, learner_id),
               names_to = "Metrics",
               values_to = "Performance") %>%
  mutate(Metrics = ifelse (Metrics == "auc", "AUC",
                   ifelse (Metrics == "acc", "ACC",
                   ifelse (Metrics == "sens", "Sens",
                   ifelse (Metrics == "spec", "Specs",
                   ifelse (Metrics == "precision", "Precs", "F1"))))))


perf.df <- perf %>%
  dplyr::select (-c(resampling_id, iteration)) %>%
  pivot_longer(cols = matches("classif"),
               names_to = "Metrics",
               values_to = "Performance") %>%
  mutate(task_id = ifelse (task_id == "neckpain", "Neck pain",
                           ifelse (task_id == "armpain", "Arm pain", "Disability"))) %>%
  mutate(learner_id = ifelse (learner_id == "scale.log", "Logistic",
                      ifelse (learner_id == "scale.encode.kknn.tuned", "Knn",
                      ifelse (learner_id == "scale.encode.xgb.tuned", "Xgb",
                      ifelse (learner_id == "scale.encode.lasso.tuned", "Lasso",
                      ifelse (learner_id == "scale.encode.rf.tuned", "RF",
                      ifelse (learner_id == "scale.encode.svm.tuned", "Svm", "ANN"))))))) %>%
  mutate(Metrics = ifelse (Metrics == "classif.auc", "AUC",
                   ifelse (Metrics == "classif.acc", "ACC",
                   ifelse (Metrics == "classif.sensitivity", "Sens",
                   ifelse (Metrics == "classif.specificity", "Specs",
                   ifelse (Metrics == "classif.precision", "Precs", "F1")))))) %>%
  bind_rows(step_perf) %>%
  mutate (task_id = factor (task_id,
                            levels = c("Arm pain", "Neck pain", "Disability"))) %>%
  mutate (Metrics = factor (Metrics,
                            levels = c("AUC", "ACC", "Precs", "F1", "Sens", "Specs"))) %>%
  filter (learner_id != "Logistic") %>%
  mutate (learner_id = factor (learner_id,
                               levels = c("Stepwise", "Knn",
                                          "Lasso", "Xgb", "RF", "Svm", "ANN")))



pred_plot1 <- perf.df %>%
  ggplot() +
  geom_bar(aes (x = Metrics, y = Performance, fill = learner_id),
           position = "dodge", stat = "identity") +
  facet_wrap(~ task_id, ncol = 1) +
  scale_fill_manual(values =  colz) +
  theme_cowplot() +
  theme(axis.text.x = ggplot2::element_text(angle = 45, hjust = 1)) +
  guides(fill=guide_legend(title="Learners"))

pred_plot1


ggsave (filename = "fig1.png",
        plot = pred_plot1,
        device = "png",
        path = "manuscript",
        width = 8,
        height = 5,
        units = "in",
        dpi = 150)

perf.df <- perf.df %>%
  mutate_if(is.numeric, round, 3)

perf.df %>%
  filter (Metrics == "Specs") %>%
  group_by(task_id) %>%
  slice_max (Performance)

perf.df %>%
  filter (Metrics == "AUC") %>%
  group_by(task_id) %>%
  slice_min (Performance)

# Extract hyperparameters selected ---------------------------------------------

tune_res <- extract_inner_tuning_results(bmr)

tune_res2 <- tune_res %>%
  pivot_longer(cols = c("kknn.k": "svm.gamma"),
               names_to = "hyperprms",
               values_to = "params") %>%
  dplyr::select (task_id, learner_id, hyperprms, params, classif.auc) %>%
  na.omit() %>%
  mutate(task_id = ifelse (task_id == "neckpain", "Neck pain",
                           ifelse (task_id == "armpain", "Arm pain", "Disability"))) %>%
  mutate (task_id = factor (task_id,
                            levels = c("Arm pain", "Neck pain", "Disability"))) %>%
  mutate(learner_id = ifelse (learner_id == "scale.log", "Logistic",
                              ifelse (learner_id == "scale.encode.kknn.tuned", "Knn",
                              ifelse (learner_id == "scale.encode.xgb.tuned", "Xgb",
                              ifelse (learner_id == "scale.encode.lasso.tuned", "Lasso",
                              ifelse (learner_id == "scale.encode.rf.tuned", "RF",
                              ifelse (learner_id == "scale.encode.svm.tuned", "Svm", "NNet"))))))) %>%
  mutate (hyperprms = str_remove(hyperprms, ".*\\.")) %>%
  mutate_if(is.numeric, round, 2)


# Export to word
my_path <- paste0("manuscript/table_",
                  "hyperparams",
                  ".docx")

ft <- flextable(tune_res2) %>%
  autofit()

my_doc <- read_docx()  %>%
  body_add_flextable(ft)

print (my_doc, target = my_path)


# Interpretable ML -------------------------------------------------------------

bmr2 <- as.data.table(bmr) %>%
  mutate (Model = mlr3misc::map (learner, "model"))

####################### Arm pain ###############################################
df <- ap_dat
x <- df[which(names(df) != "outcome")]
y <- df$outcome

for (n in seq_along (bmr2$Model)) {

  bmr2$iml_model[[n]] <- Predictor$new(bmr2$Model[[n]][[1]], data = x, y = y)

}

for (n in seq_along (bmr2$Model)[-c(1, 8, 15)]) {

  bmr2$effect [[n]] <- FeatureImp$new(bmr2$iml_model[[n]], loss = "ce")

}

featimp <- list()
featimp_gg <- list()

for (n in seq_along (bmr2$Model)[-c(1, 8, 15)]) {

  featimp [[n]] <- FeatureImp$new(bmr2$iml_model[[n]], loss = "ce")

}


for (n in c(2, 3, 5, 6, 7, 9, 10, 12, 13, 14, 16, 17, 19, 20, 21)) {

  featimp_gg[[n]] <- featimp[[n]]$plot()

}

mody_gg <- function (x) {

  x +
    xlim (0.8, 2.5)
}

featimp_gg <- featimp_gg %>%
  purrr::discard(is.null) %>%
  purrr::map (~ .x +
                xlim (0.8, 3) +
                theme_cowplot() +
                theme (axis.text.y = element_text(size = 10)))

pdf ("output/featimp.pdf", height = 20, width = 8)
plot_grid(plotlist = featimp_gg,
          ncol = 2,
          nrow = 8)

dev.off()

sessionInfo()