Last updated: 2020-10-26

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Rmd fe17d91 bernard-liew 2020-10-26 initial analysis

Introduction

This is an example of a Bayesian network, with directed arcs. I only perform the analysis on a subset of provided variables.

Import libraries

rm (list = ls())
# Helper
library (tidyverse)

# BN
library (bnlearn)

# Model
library (caret)

# Feature parallel
library (doParallel)

# Plot
library (Rgraphviz)

Import data

dat <- readRDS ("output/dat.RDS")

Collapse variables

dat <- dat %>%
  mutate (ppt_medn_base = (ppt_medn_aff_base + ppt_medn_naff_base)/2,
          ppt_uln_base = (ppt_uln_aff_base + ppt_uln_naff_base)/2,
          ppt_radn_base = (ppt_radn_aff_base + ppt_radn_naff_base)/2,
          ppt_neck_base = (ppt_neck_aff_base + ppt_neck_naff_base)/2,
          ppt_cts_base = (ppt_cts_aff_base + ppt_cts_naff_base)/2,
          ppt_ta_base = (ppt_ta_aff_base + ppt_ta_naff_base)/2) %>%
  select (-c(ppt_medn_aff_base:ppt_ta_naff_base))

BN analysis

Create blacklist

var.excl <- c(grep ("groc", names (dat), value = TRUE) ,
              grep ("worst", names (dat), value = TRUE) ,
              grep ("base", names (dat), value = TRUE) ,
              "age", "pain_years", "pain_extent", "aff_side", "emg")
df.bn = as.data.frame (dat)[, !names (dat) %in% var.excl] %>%
  na.omit()

df.bn$grp <- factor (df.bn$grp)

rx.var <- "grp"
demo.var = grep("age|sex|years|emg", colnames (df.bn), value = TRUE)
base.var = grep("_base", colnames (df.bn), value = TRUE)
mth1.var = grep("_1", colnames (df.bn), value = TRUE)
mth3.var = grep("_3", colnames (df.bn), value = TRUE)
mth6.var = grep("_6", colnames (df.bn), value = TRUE)
outcome.var = grep("_12", colnames (df.bn), value = TRUE)

pair_var <- expand.grid(from = names (df.bn),
                        to = names (df.bn)) %>%
  rownames_to_column()

tiers_keep <- pair_var %>%
  filter (!(grepl (paste0(outcome.var, collapse = "|"),from))) %>%
  filter (!(grepl (paste0(rx.var, collapse = "|"),to))) %>%
  filter (!(grepl (paste0(mth6.var, collapse = "|"), from) & 
              grepl (paste0(c(demo.var, base.var, mth1.var, mth3.var), collapse = "|"),to))) %>%
  filter (!(grepl (paste0(mth3.var, collapse = "|"), from) & 
              grepl (paste0(c(demo.var, base.var, mth1.var), collapse = "|"),to))) #%>%
  # filter (!(grepl (paste0(mth1.var, collapse = "|"), from) & 
  #           grepl (paste0(c(demo.var, base.var), collapse = "|"),to))) %>%
  # filter (!(grepl (paste0(base.var, collapse = "|"), from) & 
  #         grepl (paste0(c(demo.var), collapse = "|"),to)))

bl <- anti_join(pair_var, tiers_keep, by = "rowname")  %>%
  filter (from != to) %>%
  select (from, to)

Build the final model using model averaging

boot <- boot.strength(df.bn,
                      R = 200,
                      algorithm = "hc",
                      algorithm.args = list (blacklist = bl))

Get averaged model

avg <-  averaged.network(boot, threshold = 0.5)
fit <-  bn.fit (avg, df.bn, method = "mle")
g <- strength.plot(avg, boot, shape = "ellipse")

graph::nodeRenderInfo(g) = list(fontsize=18)
Rgraphviz::renderGraph(g)

Performance evaluation using nested cross validation.

Not run yet.

Inner is bootstrap resampling for model averaging. Outer is bootstrap resampling k = 25 for performance evaluation.

set.seed (2564)

flds <- createFolds(1:nrow(df.bn), 
                            k = 10, returnTrain = TRUE)
n_boot = 200
doParallel::registerDoParallel(7)

corr.df.list <- list()

for (k in seq_along(flds)) {
  
  train <-  df.bn [flds[[k]], ] %>% as.data.frame()
  test <- df.bn [-flds[[k]], ] %>% as.data.frame()
  
  doParallel::registerDoParallel(7)
  ############
  
  boot  =  foreach (B = 1: n_boot) %dopar%{
      boot.sample = train[sample(nrow(train), 
                                            nrow(train), replace = TRUE), ]
      bnlearn::structural.em(boot.sample, impute = "bayes-lw", max.iter = 5,
                                maximize.args = list(blacklist = bl,  
                                                      k = log(nrow(boot.sample))))
  }
  #############
  stopImplicitCluster()
  
  bootstr <-  custom.strength(boot, nodes = names(train))
  avg <-  averaged.network(bootstr, threshold = 0.7)
  fit <-  bn.fit (avg, train, method = "mle")
  
  imp.list = impute (fit, data = test, method = "bayes-lw")
  inames = names (imp.list) [-c(1:2)]
  corr.df =  structure(numeric(length (inames)), names = inames)
  
  for (var in inames) {
      corr.df[var] = cor(predict(fit, data = imp.list, var, method = "bayes-lw"), 
                         imp.list[, var])
    }
  
  corr.df.list[[k]] <- corr.df
  

}

corr.df <- bind_cols (corr.df.list) %>%
  apply (1, mean)

names (corr.df) <- inames

corr.df

Save data

save(avg, 
     bl, 
     demo.var,
     mth3.var,
     mth6.var,
     outcome.var,
     boot, 
     bootstr, 
     corr.df, 
     corr.df.list, 
     df.bn, 
     fit,
     file = "output/bn_data.RData")

sessionInfo()
R version 3.6.0 (2019-04-26)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 18362)

Matrix products: default

locale:
[1] LC_COLLATE=English_United Kingdom.1252 
[2] LC_CTYPE=English_United Kingdom.1252   
[3] LC_MONETARY=English_United Kingdom.1252
[4] LC_NUMERIC=C                           
[5] LC_TIME=English_United Kingdom.1252    

attached base packages:
[1] grid      parallel  stats     graphics  grDevices utils     datasets 
[8] methods   base     

other attached packages:
 [1] Rgraphviz_2.22.0    graph_1.56.0        BiocGenerics_0.24.0
 [4] doParallel_1.0.15   iterators_1.0.10    foreach_1.4.4      
 [7] caret_6.0-84        lattice_0.20-38     bnlearn_4.5        
[10] forcats_0.4.0       stringr_1.4.0       dplyr_1.0.2        
[13] purrr_0.3.3         readr_1.3.1         tidyr_1.0.2        
[16] tibble_3.0.3        ggplot2_3.2.1       tidyverse_1.3.0    

loaded via a namespace (and not attached):
 [1] nlme_3.1-139       fs_1.3.0           lubridate_1.7.4    DiceDesign_1.8-1  
 [5] httr_1.4.1         rprojroot_1.3-2    tools_3.6.0        backports_1.1.4   
 [9] R6_2.4.0           rpart_4.1-15       DBI_1.0.0          lazyeval_0.2.2    
[13] colorspace_1.4-1   nnet_7.3-12        withr_2.1.2        tidyselect_1.1.0  
[17] compiler_3.6.0     git2r_0.27.1       cli_2.0.1          rvest_0.3.5       
[21] xml2_1.2.2         scales_1.1.1       digest_0.6.19      rmarkdown_2.3     
[25] pkgconfig_2.0.2    htmltools_0.4.0    lhs_1.0.1          dbplyr_1.4.4      
[29] rlang_0.4.7        readxl_1.3.1       rstudioapi_0.11    generics_0.0.2    
[33] jsonlite_1.6       ModelMetrics_1.2.2 magrittr_1.5       Matrix_1.2-17     
[37] Rcpp_1.0.2         munsell_0.5.0      fansi_0.4.0        GPfit_1.0-8       
[41] lifecycle_0.2.0    stringi_1.4.3      whisker_0.3-2      yaml_2.2.0        
[45] MASS_7.3-51.4      plyr_1.8.4         recipes_0.1.9      blob_1.2.1        
[49] promises_1.0.1     crayon_1.3.4       haven_2.2.0        splines_3.6.0     
[53] hms_0.5.3          knitr_1.27         pillar_1.4.3       dials_0.0.4       
[57] stats4_3.6.0       reshape2_1.4.3     codetools_0.2-16   parsnip_0.0.5     
[61] reprex_0.3.0       glue_1.4.2         evaluate_0.14      data.table_1.12.8 
[65] modelr_0.1.5       vctrs_0.3.4        httpuv_1.5.2       cellranger_1.1.0  
[69] gtable_0.3.0       assertthat_0.2.1   xfun_0.7           gower_0.2.0       
[73] prodlim_2018.04.18 broom_0.5.4        later_0.8.0        class_7.3-15      
[77] survival_2.44-1.1  timeDate_3043.102  workflowr_1.6.2    lava_1.6.5        
[81] workflows_0.1.0    ellipsis_0.3.0     ipred_0.9-9