如何在R中的组内排名? [英] How to rank within groups in R?

问题描述

好的，看看这个数据框...

OK, check out this data frame...

  customer_name order_dates order_values
1          John  2010-11-01           15
2           Bob  2008-03-25           12
3          Alex  2009-11-15            5
4          John  2012-08-06           15
5          John  2015-05-07           20

假设我想添加一个订单变量，该变量按名称，按最大订单日期，使用决胜局的最后一个订单日期对最高订单值进行排名.因此，最终数据应如下所示:

Lets say I want to add an order variable that Ranks the highest order value, by name, by max order date, using the last order date at the tie breaker. So, ultimately the data should look like this:

  customer_name order_dates order_values ranked_order_values_by_max_value_date
1          John  2010-11-01           15                               3
2           Bob  2008-03-25           12                               1
3          Alex  2009-11-15            5                               1
4          John  2012-08-06           15                               2
5          John  2015-05-07           20                               1

凡是每个人的单笔订单都得1，之后的所有订单都按数值排序，决胜局是最后一个订单日期获得优先权.在此示例中，John 的 8/6/2012 订单排名 #2，因为它是在 11/1/2010 之后放置的.5/7/2015 订单是 1，因为它是最大的.因此，即使该订单是 20 年前下的，它也应该是排名第一的，因为它是 John 的最高订单价值.

Where everyone's single order gets 1, and all subsequent orders are ranked based on the value, and the tie breaker is the last order date getting priority. In this example, John's 8/6/2012 order gets the #2 rank because it was placed after 11/1/2010. The 5/7/2015 order is 1 because it was the biggest. So, even if that order was placed 20 years ago, it should be the #1 Rank because it was John's highest order value.

有谁知道我如何在 R 中做到这一点?我在哪里可以在数据框中的一组指定变量中进行排名?

Does anyone know how I can do this in R? Where I can Rank within a group of specified variables in a data frame?

感谢您的帮助！

推荐答案

您可以使用 dplyr

library(dplyr)
df %>%
    group_by(customer_name) %>%
    mutate(my_ranks = order(order(order_values, order_dates, decreasing=TRUE)))

Source: local data frame [5 x 4]
Groups: customer_name

  customer_name order_dates order_values my_ranks
1          John  2010-11-01           15        3
2           Bob  2008-03-25           12        1
3          Alex  2009-11-15            5        1
4          John  2012-08-06           15        2
5          John  2015-05-07           20        1

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