#------------------------------------------------------------
# Example Frequency Table Using Built-in mtcars Dataset
#------------------------------------------------------------

library(dplyr)
library(knitr)

#------------------------------------------------------------
# Load Data
#------------------------------------------------------------

data("mtcars")

# Create a working copy
cars <- mtcars

# Create a year-like variable for demonstration
cars$year <- ifelse(cars$cyl == 4, 2012,
                    ifelse(cars$cyl == 6, 2013, 2014))

#------------------------------------------------------------
# Examine Distribution of Year
#------------------------------------------------------------

table(cars$year)

#------------------------------------------------------------
# Create Frequency Table for Year 2012
#------------------------------------------------------------

freq.df <- cars %>%
  filter(year == 2012) %>%
  group_by(
    year,
    am,      # transmission
    gear,    # number of gears
    carb     # number of carburetors
  ) %>%
  summarise(count = n(), .groups = "drop")

# Convert tibble to data frame
freq.df <- data.frame(freq.df)

#------------------------------------------------------------
# Create Total Row
#------------------------------------------------------------

last.row <- c(
  "Total",
  rep("-", ncol(freq.df) - 2),
  prettyNum(sum(freq.df$count), big.mark = ",")
)

#------------------------------------------------------------
# Format Counts
#------------------------------------------------------------

freq.df2 <- within(freq.df, {
  count <- prettyNum(count, big.mark = ",")
})

#------------------------------------------------------------
# Write Output to a Text File
#------------------------------------------------------------

options(width = 120)

sink("mtcars_frequency_table.txt")

final.table <- rbind(freq.df2, last.row)

kable(final.table, format = "markdown")

sink()

#------------------------------------------------------------
# Display Table in Console
#------------------------------------------------------------

print(final.table)