R: RunningTotal in the last 365 days window by Name

Question

This is what my data looks like. The rightmost column is my Desired Column.

Name  EventType  EventDate  SalesAmount RunningTotal Runningtotal(prior365Days)
John    Email      1/1/2014      0          0            0
John    Sale       2/1/2014     10          10           10
John    Sale       7/1/2014     20          30           30
John    Sale       4/1/2015     30          60           50 
John    Webinar    5/1/2015      0          60           50
Tom     Email      1/1/2014      0          0            0
Tom     Sale       2/1/2014     15          15           15
Tom     Sale       7/1/2014     10          25           25
Tom     Sale       4/1/2015     25          50           35 
Tom     Webinar    5/1/2015      0          50           35

I am just trying to get the running total of SalesAmount for each name in the last 365 days window. For the general "RunningTotal" column I used:

df<- df%>%
   group_by (Name)%>%
    mutate(RunningTotal = cumsum(SalesAmount))

But I dont know how to get the running total only in the last 365 day window.Kindly help. Your help is sincerely appreciated!

Answer 1

df$EventDate <- as.Date(df$EventDate, format="%d/%m/%Y")
df <- df %>%
   group_by (Name) %>%
   arrange(EventDate) %>% 
   mutate(day = EventDate - EventDate[1])

f <- Vectorize(function(i)
    sum(df[df$Name[i] == df$Name & df$day[i] - df$day >= 0 & 
             df$day[i] - df$day <= 365, "SalesAmount"]), vec="i")
df$RunningTotal365 <- f(1:nrow(df))