根据数据框中存在的名义变量生成代码

Question

我有一个包含 1000 个观察值的数据框，它的结构如下。

Town <- c("TownA", "TownB", "TownC","TownD","Town A", "Town Z")
Ward <- c("Ward B","Ward Z","Ward A","Ward W","Ward X", "Ward ")
DF <- data.frame(Town, Ward)

我有另一个数据集，其中包含代表 Town 和 Ward 的名义观察值的代码。代码是用于分析的代码。例如，A 镇的代码为 23，B 镇的代码为 15，Z 镇的代码为 7。除了手动创建新列并根据城镇填充代码之外，还有没有更简单的方法在 R 中执行此操作？

我的目标是改变一个新的列，将代码与城镇相匹配。该数据集包含大约 200 个城镇。

Answer 1

您可以创建一个新的代码表，然后加入：

library(tidyverse)

Town <- c("TownA", "TownB", "TownC","TownD","Town A", "Town Z")
Ward <- c("Ward B","Ward Z","Ward A","Ward W","Ward X", "Ward ")
DF <- data.frame(Town, Ward)

codes <- tribble(
  ~Town, ~Code,
  "TownA", 23,
  "TownB", 15,
  "Town Z", 7
)
codes
#> # A tibble: 3 × 2
#>   Town    Code
#>   <chr>  <dbl>
#> 1 TownA     23
#> 2 TownB     15
#> 3 Town Z     7

DF %>%
  left_join(codes)
#> Joining, by = "Town"
#>     Town   Ward Code
#> 1  TownA Ward B   23
#> 2  TownB Ward Z   15
#> 3  TownC Ward A   NA
#> 4  TownD Ward W   NA
#> 5 Town A Ward X   NA
#> 6 Town Z  Ward     7

^{由reprex package (v2.0.1) 于 2021-09-20 创建}