小编Qui*_*c22的帖子

不明白为什么我的超前和滞后功能忽略了group by。这是一个简单的例子（实际上我需要按 5 列分组）。?

# Dummy DataSet
df <- data.frame(group = c("a","a","a","a", "a", "b", "b", "b", "b", "b"),
                 order = c(3, 4, 2, 5, 1, 1, 3, 4, 2, 4),
                 value = c(15, 22, 43, 31, 25, 11, 37, 24, 18, 9))    

"group" "order" "value"
"a" 3   15
"a" 4   22
"a" 2   43
"a" 5   31
"a" 1   25
"b" 1   11
"b" 3   37
"b" 4   24
"b" 2   18
"b" 4   9

试过这个，但即使是 order by 在这里也不起作用

df …