Question

我想根据变量的最小值对我的tbl进行子集化。

我使用data.table找到了一个SO帖子here。有没有办法使用dplyr？

> glimpse(x)
Observations: 3,074,921
Variables: 9
$ sessionId <chr> "1468614023881.kvz0h9ofxbt9", "1469063434066.e9h65wdygb9", "1469240810386.2k47r07tx1or", "146933076...
$ dateHour    <chr> "2016080106", "2016080118", "2016080119", "2016080120", "2016080108", "2016080106", "2016080117", "...
$ minute      <ord> 25, 10, 30, 38, 32, 12, 42, 32, 42, 39, 32, 20, 0, 4, 39, 46, 54, 32, 46, 46, 33, 53, 51, 2, 22, 36...
$ userType    <chr> "New Visitor", "New Visitor", "New Visitor", "New Visitor", "New Visitor", "New Visitor", "Returnin...
$ region      <chr> "Virginia", "Washington", "Chihuahua", "Missouri", "Nevada", "Minnesota", "Oklahoma", "(not set)", ...
$ metro       <chr> "Roanoke-Lynchburg VA", "Seattle-Tacoma WA", "(not set)", "Joplin MO-Pittsburg KS", "Reno NV", "Min...
$ city        <chr> "Roanoke", "Camano Island", "Ciudad Juarez", "Joplin", "Reno", "Owatonna", "Edmond", "Port-au-Princ...
$ sessions    <dbl> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...
$ dhm         <chr> "201608010625", "201608011810", "201608011930", "201608012038", "201608010832", "201608010612", "20...

dhm变量是dateHour和minute列的串联。我的数据有一些重复的会话ID，我想检索行，如果是重复的话，我会根据min（dhm）得到sessionId的最早条目。

Answer 1

每个会话分组数据并按dhm排列。然后只筛选出第一行（每个会话）

dat %>% group_by(sessions) %>% arrange(dhm) %>% filter(row_number() == 1)

或在评论中指出

dat %>% group_by(sessions) %>% filter(which.min(dhm)==row_number())

用dplyr分组最小或最大？

1 个答案: