r 将月份年份转换为有序数字

Question

我有一个包含列的数据集，其中值是

month year

，格式如下

 M_Yr
 March 1990
 April 1990
 May   1990
 June  1990
 July  1990
 Aug   1990
 Sept  1990
 Oct   1990
 Nov   1990
 Dec   1990
 Jan   1991
 Feb   1991
 March 1991
 April 1991
 May   1991
 June  1991
 July  1991
 Aug   1991
 Sept  1991
 Oct   1991
 Nov   1991
 Dec   1991

我喜欢将其转换为这样的数值

 M_Yr         Col1
 March 1990   1
 April 1990   2
 May   1990   3
 June  1990   4
 July  1990   5
 Aug   1990   6
 Sept  1990   7
 Oct   1990   8
 Nov   1990   9
 Dec   1990   10
 Jan   1991   11
 Feb   1991   12
 March 1991   13
 April 1991   14
 May   1991   15
 June  1991   16
 July  1991   17
 Aug   1991   18
 Sept  1991   19
 Oct   1991   20
 Nov   1991   21
 Dec   1991   22

我尝试过这种方法。

 df$Col1 <- as.numeric(df$M_Yr)

这确实将

month Year

变量转换为数字，但顺序是混乱的并且顺序不正确。所以我想知道什么是创建这个数字变量而不需要编写冗长的

case_when

语句的有效方法。

非常感谢任何建议。谢谢。

Answer 1

一种方法是将日期字符串转换为日期并获取它们的顺序。这是使用

lubridate

包的一种方法：

library(lubridate)
library(dplyr)

df %>%
  mutate(date = my(M_Yr),
         numeric = order(date))

输出：

         M_Yr       date numeric
1  March 1990 1990-03-01       1
2  April 1990 1990-04-01       2
3  May   1990 1990-05-01       3
4  June  1990 1990-06-01       4
5  July  1990 1990-07-01       5
6  Aug   1990 1990-08-01       6
7  Sept  1990 1990-09-01       7
8  Oct   1990 1990-10-01       8
9  Nov   1990 1990-11-01       9
10 Dec   1990 1990-12-01      10
11 Jan   1991 1991-01-01      11
12 Feb   1991 1991-02-01      12
13 March 1991 1991-03-01      13
14 April 1991 1991-04-01      14
15 May   1991 1991-05-01      15
16 June  1991 1991-06-01      16
17 July  1991 1991-07-01      17
18 Aug   1991 1991-08-01      18
19 Sept  1991 1991-09-01      19
20 Oct   1991 1991-10-01      20
21 Nov   1991 1991-11-01      21
22 Dec   1991 1991-12-01      22



dput(df)
structure(list(M_Yr = c("March 1990", "April 1990", "May   1990", 
"June  1990", "July  1990", "Aug   1990", "Sept  1990", "Oct   1990", 
"Nov   1990", "Dec   1990", "Jan   1991", "Feb   1991", "March 1991", 
"April 1991", "May   1991", "June  1991", "July  1991", "Aug   1991", 
"Sept  1991", "Oct   1991", "Nov   1991", "Dec   1991")), class = "data.frame", row.names = c(NA, 
-22L))