[英]Assign a value to previous rows based on a condition in a group using R
I have a data frame, sorted by groupID and date 我有一个数据框,按groupID和日期排序
> d1 <- data.frame(groupID = c(1,1,1,1,1,3,3,3,3),
date = c(1,2,3,4,5,6,7,8,9),
value = c(1,1,25,1,1,25,1,25,1))
>d1
groupID date value
1 1 1
1 2 1
1 3 25
1 4 1
1 5 1
3 6 25
3 7 1
3 8 25
3 9 1
I want to create a new column for each group with dates of the latest 25 value. 我想为每个组创建一个新列,其日期的最新值为25。
I intent to see the following output 我打算看下面的输出
groupID date value newvalue
1 1 1 3
1 2 1 3
1 3 25 3
1 4 1 NA
1 5 1 NA
3 6 25 6
3 7 1 8
3 8 25 8
3 9 1 NA
I have tried Assign value to group based on condition in column and if-else, but I have been unsuccessful with my attempts. 我曾尝试根据列和if-else中的条件将值分配给组 ,但是我的尝试没有成功。
You can use dplyr/tidyr to do this 您可以使用dplyr / tidyr执行此操作
library(dplyr)
library(tidyr)
df<- data.frame(groupID = c(1,1,1,1,1,3,3,3,3),
date = c(1:9),
value = c(1,1,25,1,1,25,1,25,1))
df <- df %>%
group_by(groupID) %>%
mutate(newvalue = ifelse(value == 25,date,NA)) %>%
fill(newvalue, .direction = "up")
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