R代码可基于多个变量分配序列 [英] R code to assign a sequence based off of multiple variables

问题描述

我的数据结构如下:

ID   Day   Desired Output
1    1      1
1    1      1
1    1      1
1    2      2
1    2      2
1    3      3
2    4      1
2    4      1
2    5      2
3    6      1
3    6      1

是否可以在不使用循环的情况下为所需的输出创建序列?该数据集非常大，因此无法使用循环，是否可以使用dplyr软件包或cumsum/diff的组合来做到这一点?

Is it possible to create a sequence for the desired output without using a loop? The dataset is quite large so a loop won't work, is it possible to do this with the dplyr package or maybe a combination of cumsum/diff?

推荐答案

一个选项是按'ID'分组，然后在'Day'上使用'Day'列的unique值进行match

An option is to group by 'ID', and then do a match on the 'Day' with the unique values of 'Day' column

library(dplyr)
df1 %>% 
    group_by(ID) %>% 
    mutate(desired = match(Day, unique(Day))) 

数据

df1 <- structure(list(ID = c(1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 3L, 
3L), Day = c(1L, 1L, 1L, 2L, 2L, 3L, 4L, 4L, 5L, 6L, 6L)), row.names = c(NA, 
-11L), class = "data.frame")

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