library(tidyverse)
library(rmdformats)
library(knitr)
library(kableExtra)
library(formattable)
library(caTools)
library(yardstick)
library(gplots)

data <- read_csv('https://raw.githubusercontent.com/oggyluky11/DATA-612-2020-SUMMER/master/Project%201/McDonald%20Meal%20Friend%20Rating.csv')
data

data %>% 
  mutate_if(is.character,as.factor) %>% 
  summary(maxsum = 20)

data %>% 
  spread(key = `Combo Meal`, value = Rating) %>%
  gather(key = `Combo Meal`, value = Rating, - Customer) %>%
  mutate_if(is.character,as.factor) %>% 
  summary(maxsum = 20)

data %>%
  spread(key = `Combo Meal`, value = Rating) %>%
  column_to_rownames('Customer') %>%
  as.matrix() %>%
  heatmap.2(trace = 'none',
            density.info = 'none',
            dendrogram = 'none',
            Rowv = FALSE,
            Colv = FALSE,
            col = colorRampPalette(c("grey", "deeppink4"))(n = 299))

set.seed(3)
data_split <- data %>%
  mutate(Data_Group = sample.split(Rating, 0.85)) %>%
  mutate(Data_Group = if_else(Data_Group==TRUE, 'Train', 'Test'))
data_train <- data_split %>% 
  filter(Data_Group == 'Train') %>%
  select(-Data_Group)
data_test <- data_split %>% 
  filter(Data_Group == 'Test') %>%
  select(-Data_Group) 
data_split %>%
  mutate(
  Data_Group = cell_spec(Data_Group, background = if_else(Data_Group == 'Test',
                                                    'lightpink','lightblue'))) %>%
  kable(escape = FALSE) %>%
  kable_styling(bootstrap_options = c("striped", "bordered"),
                full_width = FALSE,
                font_size = 12) %>%
  add_header_above(c('Train_Test_Split' = 4)) %>%
  scroll_box(width = "100%", height = "400px")

options(knitr.kable.NA = '?')
data_split %>% 
  mutate(Rating = cell_spec(Rating,'html',
                            background  = if_else(Data_Group == 'Test','lightpink','lightblue'))) %>%
  select(-Data_Group) %>%
  spread(`Combo Meal`, Rating) %>%
  arrange(desc(Customer)) %>%
  kable(escape = FALSE, caption = 'User-Item Matrix', align = 'lccccccccccc') %>%
  kable_styling(bootstrap_options = c("striped", "bordered"),
                full_width = FALSE,
                font_size = 12) %>%
  add_header_above(c('User', 'Item' = 11)) %>%
  footnote(symbol = 'The numbers in BLUE are training set, and those in RED are test set') 

mean_train_raw <- mean(data_train$Rating)
print(str_c('Raw average rating for every user-item combination: ', as.character(mean_train_raw)))

RMSE_train_raw <- (data_train$Rating - mean_train_raw)^2 %>% mean() %>% sqrt()
print(str_c('RMSE of raw average rating for training set: ', as.character(RMSE_train_raw)))

RMSE_test_raw <- (data_test$Rating - mean_train_raw)^2 %>% mean() %>% sqrt()
print(str_c('RMSE of raw average rating for test set: ', as.character(RMSE_test_raw)))

options(knitr.kable.NA = '')
user_bias_tb <- data_train %>% 
  group_by(Customer) %>%
  summarise(User_Bias = mean(Rating) - mean_train_raw)
item_bias_tb <- data_train %>%
  group_by(`Combo Meal`) %>%
  summarise(Item_Bias = mean(Rating) - mean_train_raw)
user_bias_tb %>% 
  arrange(desc(User_Bias)) %>%
  data.frame(row.names = NULL) %>%
  merge(item_bias_tb %>% 
          arrange(desc(Item_Bias)) %>%
          data.frame(row.names = NULL), by = 0, all = TRUE) %>%
  arrange(desc(User_Bias)) %>%
  select(-Row.names) %>%
  kable(escape = FALSE, caption = 'Bias') %>%
  add_header_above(c('Bias for User' = 2, 'Bias for Item' = 2)) 

baseline_pred <- data.frame('Customer' = character(),
                            'Combo_Meal' = character(),
                            'Baseline_Predictor' = numeric(),
                            stringsAsFactors = FALSE)
for (user in data$Customer %>% unique()){
  for(item in data$`Combo Meal` %>% unique()){
    user_bias <- user_bias_tb$User_Bias[user_bias_tb$Customer == user]
    item_bias <- item_bias_tb$Item_Bias[item_bias_tb$`Combo Meal` == item]
    baseline_predictor <- pmax(pmin(mean_train_raw + user_bias + item_bias,5),1) 
    
    baseline_pred <- add_row(baseline_pred,
                             Customer = user,
                             Combo_Meal = item,
                             Baseline_Predictor = baseline_predictor)
  }
}
baseline_pred %>%
  spread(key = 'Combo_Meal', value = 'Baseline_Predictor') %>%
  kable(caption = 'Baseline Predictors') %>%
  kable_styling(bootstrap_options = "striped", 
                full_width = FALSE,
                font_size = 12) %>%
  add_header_above(c('User', 'Item' = 11))

RMSE_train_baseline_pred <- data_train %>% 
  left_join(baseline_pred, by = c('Customer' = 'Customer', 'Combo Meal' = 'Combo_Meal')) %>%
  rmse(Rating, Baseline_Predictor) %>%
  .$`.estimate`
print(str_c('RMSE of baseline predictor for training set: ', RMSE_train_baseline_pred))

RMSE_test_baseline_pred <- data_test %>% 
  left_join(baseline_pred, by = c('Customer' = 'Customer', 'Combo Meal' = 'Combo_Meal')) %>%
  rmse(Rating, Baseline_Predictor) %>%
  .$`.estimate`
print(str_c('RMSE of baseline predictor for test set: ', RMSE_test_baseline_pred))

data.frame(Metrics = c('RMSE_Train_Raw', 
                       'RMSE_Train_Baseline_Pred', 
                       '% Change in RMSE of training set',
                       'RMSE_Test_Raw', 
                       'RMSE_Test_Baseline_Pred',
                       '% Change in RMSE of Test Set'),
Value = c(RMSE_train_raw, 
          RMSE_train_baseline_pred, 
          (RMSE_train_baseline_pred - RMSE_train_raw)/RMSE_train_raw,
          RMSE_test_raw, 
          RMSE_test_baseline_pred,
          (RMSE_test_baseline_pred - RMSE_test_raw)/RMSE_test_raw),
stringsAsFactors = FALSE) %>%
  mutate(Value = case_when(str_detect(Metrics, '%') ~ cell_spec(str_c(as.character(round(Value*100,2)),'%'), bold = TRUE),
                           TRUE ~ if_else(str_detect(Metrics,'Train'),
                                          color_bar('lightblue')(Value),
                                          color_bar('lightpink')(Value))),
         Metrics = case_when(str_detect(Metrics, '%') ~ cell_spec(Metrics, bold = TRUE),
                             TRUE ~ Metrics)) %>%
  kable(escape = FALSE, caption = 'Summary',align = 'lr') %>%
  kable_styling('hover') %>%
  row_spec(c(1,2,4,5), background = 'white') %>%
  row_spec(c(3,6), background = 'lightgrey')