cumsum in grouped data with dplyr

Question

I have a data frame df (which can be downloaded here) referred to a register of companies that looks something like this:

    Provider.ID        Lo         


        

Answer 1

When you group by local.Authority & year it takes unique values and print the result as 1,-1,1 so better group by only local.Authority where cumsum works based on total values and result 1,0,1

 df <- df %>%
      group_by(Local.Authority) %>%
      mutate(cum.to = cumsum(total))

    > df
    Source: local data frame [3 x 8]
    Groups: Local.Authority [1]

      Provider.ID Local.Authority month  year entry  exit total cum.to
                              
    1 1-102642676            Kent    10  2010     1     0     1      1
    2 1-102642676            Kent     9  2011     0     1    -1      0
    3 1-102642676            Kent    10  2014     1     0     1      1