R dplyr日期过滤器基于另一个变量

Question

我试图仅根据日期过滤行，直到响应为“是” 的行，即首先是或最早是。任何帮助将不胜感激。

Date <- c("1/2/2018", "1/3/2018", "1/4/2018", "1/5/2018", "1/6/2018", "1/7/2018", "1/8/2018")
Response <- c("No", "No", "No", "Yes", "No", "No", "Yes")

df <- cbind(Date, Response)

Answer 1

假设您想保留第一个“是”响应，则可以执行以下操作：

library(dplyr)
df <- data.frame(Date, Response, stringsAsFactors = FALSE)

df %>%
  filter(cumsum(lag(Response, default = "") == "Yes") < 1)

      Date Response
1 1/2/2018       No
2 1/3/2018       No
3 1/4/2018       No
4 1/5/2018      Yes