我在单个字符串变量states_county中有州和县名称，我想将它们拆分以创建两个不同的变量 - states和county。
有些州有两个（甚至三个）单词，县也是如此。
> states_county_names_df$states_county
[1] "California San Francisco"
[2] "New York Bronx"
[3] "New York Kings"
[4] "New York New York"
[5] "New York Queens"
[6] "New York Richmond"
[7] "Washington King"
[8] "Illinois Cook"
[9] "Massachusetts Suffolk"
[10] "District of Columbia District of Columbia"
因此，我想提取美国所有州的名称来创建一个因子变量，并使用子字符串命令删除州（并获取县），同时只保留州（以删除县）。我不确定如何为states_county变量中的每个字符串条目循环每个因子变量级别。
state_name<-state.name
for(i in levels(state_name)){
print("levels(state_name)")
test<-str_remove_all(states_county_names_df$states_county, "levels(state_name)")
}
如果有人能提出不同的方法来获得结果，我将不胜感激。
我目前使用暴力并编写 50 行代码来生成州列，但仍然无法到达县，因为我不确定如何从 states_county列“减去”州列。
states_county_names_df$states[grepl("California",states_county_names_df$states_county)] <- "California"
states_county_names_df$states[grepl("New York", states_county_names_df$states_county)] <- "New York"
.
.
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R 有一个名为“state”的内置数据集，其中包含美国各州的列表。该列表中没有“哥伦比亚特区”，但您可以将其添加到列表中，然后使用该列表将“states_county”拆分为州和县，例如
library(tidyverse)
states_county_names_df <- data.frame(states_county = c(
"California San Francisco",
"New York Bronx",
"New York Kings",
"New York New York",
"New York Queens",
"New York Richmond",
"Washington King",
"Illinois Cook",
"Massachusetts Suffolk",
"District of Columbia District of Columbia"
)
)
data(state)
state.name
#> [1] "Alabama" "Alaska" "Arizona" "Arkansas"
#> [5] "California" "Colorado" "Connecticut" "Delaware"
#> [9] "Florida" "Georgia" "Hawaii" "Idaho"
#> [13] "Illinois" "Indiana" "Iowa" "Kansas"
#> [17] "Kentucky" "Louisiana" "Maine" "Maryland"
#> [21] "Massachusetts" "Michigan" "Minnesota" "Mississippi"
#> [25] "Missouri" "Montana" "Nebraska" "Nevada"
#> [29] "New Hampshire" "New Jersey" "New Mexico" "New York"
#> [33] "North Carolina" "North Dakota" "Ohio" "Oklahoma"
#> [37] "Oregon" "Pennsylvania" "Rhode Island" "South Carolina"
#> [41] "South Dakota" "Tennessee" "Texas" "Utah"
#> [45] "Vermont" "Virginia" "Washington" "West Virginia"
#> [49] "Wisconsin" "Wyoming"
states_inc_Columbia <- c(state.name, "District of Columbia")
states_county_names_df %>%
mutate(state = str_extract(states_county, paste(states_inc_Columbia, collapse = "|")),
county = str_remove(states_county, paste(states_inc_Columbia, collapse = "|")))
#> states_county state
#> 1 California San Francisco California
#> 2 New York Bronx New York
#> 3 New York Kings New York
#> 4 New York New York New York
#> 5 New York Queens New York
#> 6 New York Richmond New York
#> 7 Washington King Washington
#> 8 Illinois Cook Illinois
#> 9 Massachusetts Suffolk Massachusetts
#> 10 District of Columbia District of Columbia District of Columbia
#> county
#> 1 San Francisco
#> 2 Bronx
#> 3 Kings
#> 4 New York
#> 5 Queens
#> 6 Richmond
#> 7 King
#> 8 Cook
#> 9 Suffolk
#> 10 District of Columbia
由reprex 包于 2022 年 3 月 16 日创建(v2.0.1)
还有一个基本的 R 选项：
states_county_names_df <- data.frame(states_county = c(
"California San Francisco",
"New York Bronx",
"New York Kings",
"New York New York",
"New York Queens",
"New York Richmond",
"Washington King",
"Illinois Cook",
"Massachusetts Suffolk",
"District of Columbia District of Columbia"
)
)
data(state)
state.name
#> [1] "Alabama" "Alaska" "Arizona" "Arkansas"
#> [5] "California" "Colorado" "Connecticut" "Delaware"
#> [9] "Florida" "Georgia" "Hawaii" "Idaho"
#> [13] "Illinois" "Indiana" "Iowa" "Kansas"
#> [17] "Kentucky" "Louisiana" "Maine" "Maryland"
#> [21] "Massachusetts" "Michigan" "Minnesota" "Mississippi"
#> [25] "Missouri" "Montana" "Nebraska" "Nevada"
#> [29] "New Hampshire" "New Jersey" "New Mexico" "New York"
#> [33] "North Carolina" "North Dakota" "Ohio" "Oklahoma"
#> [37] "Oregon" "Pennsylvania" "Rhode Island" "South Carolina"
#> [41] "South Dakota" "Tennessee" "Texas" "Utah"
#> [45] "Vermont" "Virginia" "Washington" "West Virginia"
#> [49] "Wisconsin" "Wyoming"
states_inc_Columbia <- c(state.name, "District of Columbia")
states_county_names_df$state <- sapply(regmatches(x = states_county_names_df$states_county,
regexec(paste(states_inc_Columbia, collapse = "|"),
states_county_names_df$states_county)),
"[", 1)
states_county_names_df$county <- sub(x = states_county_names_df$states_county,
pattern = paste(states_inc_Columbia, collapse = "|"),
replacement = "", ignore.case = TRUE)
states_county_names_df
#> states_county state
#> 1 California San Francisco California
#> 2 New York Bronx New York
#> 3 New York Kings New York
#> 4 New York New York New York
#> 5 New York Queens New York
#> 6 New York Richmond New York
#> 7 Washington King Washington
#> 8 Illinois Cook Illinois
#> 9 Massachusetts Suffolk Massachusetts
#> 10 District of Columbia District of Columbia District of Columbia
#> county
#> 1 San Francisco
#> 2 Bronx
#> 3 Kings
#> 4 New York
#> 5 Queens
#> 6 Richmond
#> 7 King
#> 8 Cook
#> 9 Suffolk
#> 10 District of Columbia
由reprex 包于 2022 年 3 月 16 日创建(v2.0.1)