如何将值映射到数据框 R 中的值列表

Question

目前我有一个基于状态分段的数据框，例如：

  STATE     
1 Connecticut
2 Maine
3 New York
4 Pennsylvania

我希望能够根据地区对这些州进行细分，并希望有一个基于此的列：

  STATE        REGION
1 Connecticut  New England
2 Maine        New England
3 New York     Mid-Atlantic
4 Pennsylvania Mid-Atlantic

目前，我有这个：

ne <- c("Connecticut", "Maine", "Massachusetts", "New Hampshire", "Rhode Island", "Vermont")
values <- c("New England")
df$REGION <- values[match(jails_cleaned$STATE, ne)]

midatlantic <- c("New Jersey", "New York", "Pennsylvania")
values2 <- c("Mid-Atlantic")
df$REGION <- values[match(df$STATE, midatlantic)]

但是在运行这个时，它只匹配新英格兰的值而不是中大西洋。

Answer 1

创建一个数据框，您将 merge 到您的 jails_cleaned 数据

df_stats <- data.frame(
  'STATE' = c(
    c("Connecticut", "Maine", "Massachusetts", "New Hampshire", "Rhode Island", "Vermont"),
    c("New Jersey", "New York", "Pennsylvania")),
  'REGION' = c(rep("New England",6), rep("Mid-Atlantic",3))
)

df_stats
          STATE       REGION
1   Connecticut  New England
2         Maine  New England
3 Massachusetts  New England
4 New Hampshire  New England
5  Rhode Island  New England
6       Vermont  New England
7    New Jersey Mid-Atlantic
8      New York Mid-Atlantic
9  Pennsylvania Mid-Atlantic

merge(jails_cleaned,df_stats, by = 'STATE')

更新

如果要执行左连接，即保留jails_cleaned 的每一行，请使用all.x = TRUE 参数

merge(jails_cleaned,df_stats, by = 'STATE', all.x = TRUE)