Recode survey data to be consistent across multiple time points

gistfile1.r

# Recode and score variables ----
# Input: Long data set
# Output: Long data set, with fat, fibre and psychosocial score variables consistently
# coded at baseline, three months and twelve months.
# Explanation: Different people entered the baseline and follow-up survey data, and they
# didn't talk to each other. So the data for some questions got coded differently at
# different timepoints. This is very confusing, and means we can't meaningfully compare
# the data, so I'm writing this code to fix it up.
make_coding_consistent = function(data)
{
  # If the data is from baseline, leave it alone
  # If the data is from three months or twelve months, it's potentially coded differently.
  # So we have to recode it, to make it consistent.
  cols_to_recode = c("trimfatmeat", "chickentrim", "olive", "otheroil", "margarine",
                     "butter", "lowfmilk", "litecream", "lfcheese", #"spreadlowf",
                     "wholepasta", "brownrice", "breads")
  # The values in these columns have to be reversed at month 3 and month 12. So 5 becomes 1,
  # 4 becomes 2, ..., 1 becomes 5
  data[data$time %in% c(3, 12), cols_to_recode] = 6 - data[data$time %in% c(3, 12), cols_to_recode]
  
  cols_to_recode2 = c("PAtired", "PAstress", "PAdemands", "PAdepress", "diethurry",
                     "dietstress", "dietdemands", "dietdepress", "choicewgoal", "PAhelpgoal")
  data[data$time %in% c(3, 12), cols_to_recode2] = 5 - data[data$time %in% c(3, 12), cols_to_recode2]
  return(data)
}