setwd('S:/Courses/stat-renaes/Stat404')
shoes=read.sas7bdat("shoes_tracker.sas7bdat")
attach(shoes)

summary(shoes)
contents(shoes)
which(!complete.cases(shoes)) # shows which cases are incomplete
shoes[!complete.cases(shoes),]

for (Var in names(shoes)) {
  missing <- sum(is.na(shoes[,Var]))
  if (missing > 0) {
    print(c(Var,missing))
  }
}

table(Supplier_Name,useNA="ifany")
table(Supplier_ID,useNA="ifany")