Looping over spreadsheets to combine into a single dataframe

generate_df.R

library(dplyr)

# create empty dataframe
df <- data.frame(Domain=character(),
                 Total=integer(), 
                 Date=character()) 
# loop thru data files + add to data frame
for (date in c('2012-2013','2014-2015','2016-2017')) {
  # set data file path + read in data
  data <- load_data(date=date, time=365)
  # summarize pieces I need + add date identifier column
  data_summary <- data %>% 
    select(Domain, CHTC_Total) %>%
    group_by(Domain) %>%
    summarize(Total = sum(CHTC_Total)) %>%
    mutate(Date = date)
  # add to master df
  df <- rbind(df, data_summary)
}