R 将值保留到第一条记录

使用此示例：

dframe1 <- structure(list(id = c(1L, 1L, 1L, 2L, 2L), name = c("Google", 
"Yahoo", "Amazon", "Amazon", "Google"), date = c("2008-11-01", 
"2008-11-01", "2008-11-04", "2008-11-01", "2008-11-02")), class = "data.frame", row.names = c(NA, 
-5L))

dframe2 <- structure(list(id = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 2L, 2L, 2L, 2L, 2L, 2L), date = c("2008-11-01", "2008-11-01", 
"2008-11-04", "2008-10-31", "2008-10-31", "2008-11-02", "2008-11-02", 
"2008-11-02", "2008-11-05", "2008-11-02", "2008-11-03", "2008-10-31", 
"2008-11-01", "2008-11-01", "2008-11-02", "2008-11-02", "2008-11-03"
), text_sth = c("test", "text_sth", "text here", "another text", 
"other", "another one", "test", "text_sth", "text here", "another text", 
"other", "etc", "test", "text_sth", "text here", "another text", 
"text here")), row.names = c(NA, -17L), class = "data.frame")

library(dplyr)

dframe1 <- mutate(dframe1, date = as.Date(date))
dframe2 <- mutate(dframe2, date = as.Date(date))

df2 <- 
  dframe2 %>% 
  group_by(id, date) %>% 
  summarise(text_sth = paste(text_sth, collapse = " "))

left_join(dframe1, df2, by = "id") %>% 
  mutate(date_diff = as.numeric(date.y - date.x)) %>%
  filter(abs(date_diff) == 1) %>% 
  mutate(label = ifelse(date_diff == -1, "before", "after")) %>% 
  select(id, name, label, text_sth)

dframe1%
变异（标签=ifelse（日期差异==-1，“之前”，“之后”））%>%
选择（id、名称、标签、文本）

可以在特定日期范围的特定时间之前和之后保存数据

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如何根据dframe1中的特定时间修改它并将数据保留在日期之前？

您正在根据不在数据框中的列进行筛选。每行应该有一个条件语句，如果df2和dframe1的长度不相同，那么情况就不是这样了，您想要的最终结果应该是什么样子？您能否编辑您的问题并提供有关示例数据最终结果的信息？