R：拆分 - 应用 - 组合以获得累积变量答案

【问题标题】：R: Split - Apply - Combine to get cummulative variableR：拆分 - 应用 - 组合以获得累积变量
【发布时间】：2015-08-12 02:10:33
【问题描述】：

这是 df 的一个小代表：

Name <- rep(c("Kobe Bryant", "Julius Randle", "Robert Sacre" ,"Lebron James", "Kevin Love"),c(2,2,2,4,5))

Team <- rep(c("Los Angeles Lakers", "Cleveland Cavaliers"),c(6,9))

Date <- as.Date(c("2015-05-14", "2015-05-15", "2015-05-14","2015-05-18","2015-05-14", "2015-05-20", "2015-05-14","2015-05-16","2015-05-21", "2015-05-22", "2015-05-14","2015-05-16","2015-05-17","2015-06-21","2015-06-22"))

dd <- data.frame(Name,Team,Date)

我想为每个团队创建一个新变量/列，根据日期从最旧到最近的游戏对不同的游戏进行排名。

输出如下所示：

        Name                Team       Date desired_output
1    Kobe Bryant  Los Angeles Lakers 2015-05-14              1
2    Kobe Bryant  Los Angeles Lakers 2015-05-15              2
3  Julius Randle  Los Angeles Lakers 2015-05-14              1
4  Julius Randle  Los Angeles Lakers 2015-05-18              3
5   Robert Sacre  Los Angeles Lakers 2015-05-14              1
6   Robert Sacre  Los Angeles Lakers 2015-05-20              4
7   Lebron James Cleveland Cavaliers 2015-05-14              1
8   Lebron James Cleveland Cavaliers 2015-05-16              2
9   Lebron James Cleveland Cavaliers 2015-05-21              4
10  Lebron James Cleveland Cavaliers 2015-05-22              5
11    Kevin Love Cleveland Cavaliers 2015-05-14              1
12    Kevin Love Cleveland Cavaliers 2015-05-16              2
13    Kevin Love Cleveland Cavaliers 2015-05-17              3
14    Kevin Love Cleveland Cavaliers 2015-06-21              4
15    Kevin Love Cleveland Cavaliers 2015-06-22              5

我想过拆分 - 应用 - 结合排名功能，但我无法实现。

【问题讨论】：

也请与split、apply 和combine 分享您的尝试。

标签： r ranking-functions split-apply-combine

【解决方案1】：

我们可以使用来自dplyr 的dense_rank 来执行此操作：

library(dplyr)
dd %>% group_by(Team) %>%
       mutate(rank = dense_rank(Date))

            Name                Team       Date rank
1    Kobe Bryant  Los Angeles Lakers 2015-05-14    1
2    Kobe Bryant  Los Angeles Lakers 2015-05-15    2
3  Julius Randle  Los Angeles Lakers 2015-05-14    1
4  Julius Randle  Los Angeles Lakers 2015-05-18    3
5   Robert Sacre  Los Angeles Lakers 2015-05-14    1
6   Robert Sacre  Los Angeles Lakers 2015-05-20    4
7   Lebron James Cleveland Cavaliers 2015-05-14    1
8   Lebron James Cleveland Cavaliers 2015-05-16    2
9   Lebron James Cleveland Cavaliers 2015-05-21    4
10  Lebron James Cleveland Cavaliers 2015-05-22    5
11    Kevin Love Cleveland Cavaliers 2015-05-14    1
12    Kevin Love Cleveland Cavaliers 2015-05-16    2
13    Kevin Love Cleveland Cavaliers 2015-05-17    3
14    Kevin Love Cleveland Cavaliers 2015-06-21    6
15    Kevin Love Cleveland Cavaliers 2015-06-22    7

【讨论】：