Calculate number of years worked with different end dates
base R
You should use Reduce with accumulate = T.
df2$employment_history <- apply(df2[,-1], 1, function(x) sum(!Reduce(any, x==0, accumulate = TRUE)))
merge(df1, df2[c("id","employment_history")])
dplyr
Or use the built-in dplyr::cumany function:
df2 %>%
pivot_longer(-id) %>%
group_by(id) %>%
summarise(employment_history = sum(value[!cumany(value == 0)])) %>%
left_join(df1, .)
Output
id start_UI employment_history
1 R005 2012-06-10 2
2 R006 2013-01-15 3
3 R007 2014-12-21 5