smoking data: Has there been a smoker in the past

find_previous_smoker.R

# calculate if there has been a smoker in the past
 
# "smoked_previously"

data_prac <- data_frame(ID = c(1, 1, 1, 1,
                               201, 201,
                               342, 342, 342,
                               613, 613, 613, 613, 613),
                        time = c(1, 2, 3, 4,
                                 1, 2,
                                 1, 2, 3,
                                 1, 2, 3, 4, 5),
                        smoke = c("smoker", "smoker", "non_smoker", "non_smoker",
                                  "non_smoker", "smoker",
                                  "non_smoker", "non_smoker", "non_smoker",
                                  "non_smoker", "non_smoker", "smoker", "non_smoker", "non_smoker"))
#> data_prac
#> Source: local data frame [14 x 3]
#> 
#> ID  time      smoke
#> <dbl> <dbl>      <chr>
#> 1      1     1     smoker
#> 2      1     2     smoker
#> 3      1     3 non_smoker
#> 4      1     4 non_smoker
#> 5    201     1 non_smoker
#> 6    201     2     smoker
#> 7    342     1 non_smoker
#> 8    342     2 non_smoker
#> 9    342     3 non_smoker
#> 10   613     1 non_smoker
#> 11   613     2 non_smoker
#> 12   613     3     smoker
#> 13   613     4 non_smoker
#> 14   613     5 non_smoker

data_prac %>%
    group_by(ID) %>%
    arrange(time) %>%
    mutate(smoke_hist = ifelse(cumsum(smoke == "smoker") >= 1,
                               yes = "has_smoked",
                               no = "non_smoker"))

#> Source: local data frame [14 x 4]
#> Groups: ID [4]
#> 
#> ID  time      smoke smoke_hist
#> (dbl) (dbl)      (chr)      (chr)
#> 1      1     1     smoker has_smoked
#> 2      1     2     smoker has_smoked
#> 3      1     3 non_smoker has_smoked
#> 4      1     4 non_smoker has_smoked
#> 5    201     1 non_smoker non_smoker
#> 6    201     2     smoker has_smoked
#> 7    342     1 non_smoker non_smoker
#> 8    342     2 non_smoker non_smoker
#> 9    342     3 non_smoker non_smoker
#> 10   613     1 non_smoker non_smoker
#> 11   613     2 non_smoker non_smoker
#> 12   613     3     smoker has_smoked
#> 13   613     4 non_smoker has_smoked
#> 14   613     5 non_smoker has_smoked