dplyr lazyeval sample

dplyr_lazyeval.R

example <- function(df, column_name, input_vec) {
  # INPUTS:
  # df          : data frame
  # column_name : string value of column name in df 
  # input_vec   : character vector of values in column_name of df
  # OUTPUTS:
  # df          : filtered dataframe
  
  # Main reason for using this is because df$column_name throws
  # error as column_name is not a column in df
  # We need the column_name input to be used
  
  # Expressing the dplyr statement
  # column_name %in% input_vec using interp
  filter_criteria <- interp(~x %in% y, .values = list(x = as.name(column_name), y = input_vec))
  
  # filter_ instead of filter
  df %>%
    filter_(filter_criteria) -> df
    
  return(df)
}