Assign A Value of 1 or 0 based on condition

Question

I have monthly reports from October through April and have stacked all of the data. I sorted the data by UniqueID and then Date.

I want to create a dummy variable that will meet the following condition:

1.) If the last occurrence of a specific UniqueID is not in the last month (April), then I want the variable to =1, otherwise 0.

The Freq column counts how many times the UniqueID shows up in the entire dataset of stacked monthly reports.

UniqueID Date        Freq
XX343_1  02/01/2019  3
XX343_1  03/01/2019  3  
XX343_1  04/01/2019  3
SD229_1  11/01/2018  4 
SD229_1  12/01/2018  4
SD229_1  01/01/2019  4
SD229_1  02/01/2019  4
WE321_1  10/01/2018  1

Basically, I would want the following output:

UniqueID Date        Freq Dummy
XX343_1  02/01/2019  3    0
XX343_1  03/01/2019  3    0
XX343_1  04/01/2019  3    0
SD229_1  11/01/2018  4    0
SD229_1  12/01/2018  4    0
SD229_1  01/01/2019  4    0
SD229_1  02/01/2019  4    1
WE321_1  10/01/2018  1    1

The following code is what I have attempted:

 data$Dummy=ifelse(data$Date=="2018-10-01" & data$Freq==1,1,ifelse(
                   data$Date=="2018-10-01" & data$Freq>=2,0,ifelse(
                   data$Date=="2018-11-01" & data$Freq<=2,1,ifelse(
                   data$Date=="2018-11-01" & data$Freq >2,0,ifelse(
                   data$Date=="2018-12-01" & data$Freq<=3,1,ifelse(
                   data$Date=="2018-12-01" & data$Freq >3,0,ifelse(
                   data$Date=="2019-01-01" & data$Freq<=4,1,ifelse(
                   data$Date=="2019-01-01" & data$Freq >4,0,ifelse(
                   data$Date=="2019-02-01" & data$Freq<=5,1,ifelse(
                   data$Date=="2019-02-01" & data$Freq >5,0,ifelse(
                   data$Date=="2019-03-01" & data$Freq<=6,1,ifelse(
                   data$Date=="2019-03-01" & data$Freq >6,0,0
               ))))))))))))

I keep getting errors and I'm not sure how to fix my problems. I get a lot of situations where if the first occurrence of a UniqueID is not in October, then the Dummy will = 0 in the second to last month. Can someone point me in the right direction?

Answer 1

library(dplyr); library(lubridate)
data <- read.table(header = T, stringsAsFactors = F,
  text = "UniqueID Date        Freq
  XX343_1  02/01/2019  3
  XX343_1  03/01/2019  3  
  XX343_1  04/01/2019  3
  SD229_1  11/01/2018  4 
  SD229_1  12/01/2018  4
  SD229_1  01/01/2019  4
  SD229_1  02/01/2019  4
  WE321_1  10/01/2018  1"
) %>% 
  mutate(Date = mdy(Date))

---

ID_dummy <- data %>%
  group_by(UniqueID) %>%
  summarize(last_Date = max(Date))

data %>%
  left_join(ID_dummy) %>%
  mutate(Dummy = if_else(last_Date == Date & month(last_Date) != 4, 1, 0))
#Joining, by = "UniqueID"
#  UniqueID       Date Freq  last_Date Dummy
#1  XX343_1 2019-02-01    3 2019-04-01     0
#2  XX343_1 2019-03-01    3 2019-04-01     0
#3  XX343_1 2019-04-01    3 2019-04-01     0
#4  SD229_1 2018-11-01    4 2019-02-01     0
#5  SD229_1 2018-12-01    4 2019-02-01     0
#6  SD229_1 2019-01-01    4 2019-02-01     0
#7  SD229_1 2019-02-01    4 2019-02-01     1
#8  WE321_1 2018-10-01    1 2018-10-01     1