R：如何为多个值创建虚拟变量？

Question

我有一个包含多个国家/地区的数据集，我想为各大洲创建一个虚拟变量。

我的数据集现在是这样的：

+---------------+-----------+-----+-----+-----+
|    Country    |  Period   |  X  |  Y  |  Z  |
+---------------+-----------+-----+-----+-----+
| Argentina     | 1991-1995 | ... | ... | ... |
| Argentina     | 1996-2000 | ... | ... | ... |
| Bolivia       | 1991-1995 | ... | ... | ... |
| Bolivia       | 1996-2000 | ... | ... | ... |
| Brazil        | 1991-1995 | ... | ... | ... |
| Brazil        | 1996-2000 | ... | ... | ... |
| Canada        | 1991-1995 | ... | ... | ... |
| Canada        | 1996-2000 | ... | ... | ... |
| United States | 1991-1995 | ... | ... | ... |
| United States | 1996-2000 | ... | ... | ... |
+---------------+-----------+-----+-----+-----+

我想要的输出如下：

+---------------+-----------+-----+-----+-----+---------+---------+
|    Country    |  Period   |  X  |  Y  |  Z  | dummySA | dummyNA |
+---------------+-----------+-----+-----+-----+---------+---------+
| Argentina     | 1991-1995 | ... | ... | ... |       1 |       0 |
| Argentina     | 1996-2000 | ... | ... | ... |       1 |       0 |
| Bolivia       | 1991-1995 | ... | ... | ... |       1 |       0 |
| Bolivia       | 1996-2000 | ... | ... | ... |       1 |       0 |
| Brazil        | 1991-1995 | ... | ... | ... |       1 |       0 |
| Brazil        | 1996-2000 | ... | ... | ... |       1 |       0 |
| Canada        | 1991-1995 | ... | ... | ... |       0 |       1 |
| Canada        | 1996-2000 | ... | ... | ... |       0 |       1 |
| United States | 1991-1995 | ... | ... | ... |       0 |       1 |
| United States | 1996-2000 | ... | ... | ... |       0 |       1 |
+---------------+-----------+-----+-----+-----+---------+---------+

所以，我想为南美洲的所有国家和北美的所有国家建立一个虚拟模型。我知道如何为单个国家或年份创建虚拟变量，但不会为多个值创建虚拟变量。

Answer 1

如果只有少数几个国家，请使用%in% 创建虚拟列

library(dplyr)
df1 %>%
    mutate(dummySA = as.integer(Country %in% 
        c("Argentina", "Bolivia", "Brazil")), 
        dummyNA = as.integer(!dummySA))

否则，使用“国家/地区”和地理区域创建一个键/值数据集，进行合并/连接并通过 spread 创建虚拟值

library(tidyr)
df1 %>% 
   left_join(keyvaldat) %>%
   mutate(n = 1) %>%
   spread(value, n, fill = 0)