仅保留具有多个观察值的数据组 [英] Keep only groups of data with multiple observations

问题描述

我试图只保留具有多个观察结果的 deids.

I am attempting to keep only deids with multiple observations.

我有以下代码

help <- data.frame(deid = c(1, 5, 5, 5, 5, 5, 5, 12, 12, 12, 12),
                   session.number = c(1, 1, 2, 3, 4, 5, 6, 1, 2, 3, 4),
                   days.since.last = c(0, 0, 7, 14, 93, 5, 102, 0, 21, 104, 4))

   deid session.number days.since.last
1     1              1               0
2     5              1               0
3     5              2               7
4     5              3              14
5     5              4              93
6     5              5               5
7     5              6             102
8    12              1               0
9    12              2              21
10   12              3             104
11   12              4               4

我无力的尝试是使用 group_by 然后使用 filter( ) 命令

My feeble attempt was to use the group_by and then the filter( ) command

help %>% group_by(deid) %>% filter(session.number >=2)

然而，它只保持 session.number 为 2 或更大.所以我去掉了 deid = 1，但所有剩余的 deid 数据都从 session.number 2 开始，而不是 session.number 1.

However, it only keeps session.number's at 2 or greater. So I get rid of the deid = 1, but all the remaining deid data starts at session.number 2, and not session.number 1.

我想告诉 R 的是让组(deid)保持大于 1 的观察(session.number)

What I am trying to tell R is to keep the groups (deid) with greater than 1 observation (session.number)

非常感谢任何帮助.

推荐答案

应该这样做 - 您需要通过使用 n() 获得的每个组中的观察数量进行过滤:

this should do it - you need to filter by number of observations in each group which is got using n():

help %>% group_by(deid) %>% filter(n()>1)

  deid session.number days.since.last
1     5              1               0
2     5              2               7
3     5              3              14
4     5              4              93
5     5              5               5
6     5              6             102
7    12              1               0
8    12              2              21
9    12              3             104
10   12              4               4

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