如何在R中将字符列拆分为多列答案

【问题标题】：How to split a character column into multiple columns in R如何在R中将字符列拆分为多列
【发布时间】：2016-07-19 12:19:25
【问题描述】：

我有一个数据框x:

dput(x)
structure(list(District = structure(c(6L, 6L, 6L, 6L, 6L, 6L), .Label = c("District - Central (06)", 
"District - East (04)", "District - New Delhi (05)", "District - North (02)", 
"District - North East (03)", "District - North West (01)", "District - South (09)", 
"District - South West (08)", "District - West (07)"), class = "factor"), 
    Age = structure(c(103L, 1L, 2L, 14L, 25L, 36L), .Label = c("0", 
    "1", "10", "100+", "11", "12", "13", "14", "15", "16", "17", 
    "18", "19", "2", "20", "21", "22", "23", "24", "25", "26", 
    "27", "28", "29", "3", "30", "31", "32", "33", "34", "35", 
    "36", "37", "38", "39", "4", "40", "41", "42", "43", "44", 
    "45", "46", "47", "48", "49", "5", "50", "51", "52", "53", 
    "54", "55", "56", "57", "58", "59", "6", "60", "61", "62", 
    "63", "64", "65", "66", "67", "68", "69", "7", "70", "71", 
    "72", "73", "74", "75", "76", "77", "78", "79", "8", "80", 
    "81", "82", "83", "84", "85", "86", "87", "88", "89", "9", 
    "90", "91", "92", "93", "94", "95", "96", "97", "98", "99", 
    "Age not stated", "All ages"), class = "factor"), Total = c(3656539L, 
    56131L, 58644L, 63835L, 63859L, 64945L), Rural = c(213950L, 
    3589L, 3757L, 4200L, 4102L, 4223L), Urban = c(3442589L, 52542L, 
    54887L, 59635L, 59757L, 60722L)), .Names = c("District", 
"Age", "Total", "Rural", "Urban"), row.names = c(NA, 6L), class = "data.frame")

我想拆分District 列以将区名提取到新列Name。例如。 “District - North West (01)”应该拆分为“North West”。我试过str_split_fixed 得到：

x
                    District      Age   Total  Rural   Urban 1    name
1 District - North West (01) All ages 3656539 213950 3442589      North West (01)
2 District - North West (01)        0   56131   3589   52542      North West (01)
3 District - North West (01)        1   58644   3757   54887      North West (01)
4 District - North West (01)        2   63835   4200   59635      North West (01)
5 District - North West (01)        3   63859   4102   59757      North West (01)
6 District - North West (01)        4   64945   4223   60722      North West (01)

我尝试再次使用相同的函数来拆分name 列以将区域名称与代码分开，但它给了我以下错误：

stri_split_regex 中的错误（字符串，模式，n = n，简化 = TRUE，opts_regex = attr（模式，：正则表达式模式中不正确的嵌套括号。 (U_REGEX_MISMATCHED_PAREN)

有没有办法根据单个函数中的模式将字符列拆分为多列？

【问题讨论】：

你可以在这里使用Strsplit()
@PankajKaundal：我试过了，但结果是一个列表。此外，从名称中拆分代码的问题仍然是一个问题。例如。将“North West”与“(01)”分开。

标签： r split stringr

【解决方案1】：

你可以使用

library(stringr)

data.frame(str_split_fixed(df$District, " ", 3))

    X1      X2      X3
1 District   -    North West (01)
2 District   -    North West (01)
3 District   -    North West (01)
4 District   -    North West (01)
5 District   -    North West (01)
6 District   -    North West (01)

您可以使用gsub 删除您在此处拥有的多余内容，

gsub("[[:digit:]]","",df$X3)
gsub("[[:punct:]]","",df$X3)

等等

【讨论】：

您需要提及您使用的任何外部包。（顺便说一句，很好的解决方案）
或者可以直接使用data.frame(str_split_fixed(a$District, " ", 4))。谢谢！
@rar : 如果我们将其除以 4，那么 North 和 West 将进入不同的列，因为它们之间有一个空格。

【解决方案2】：

你可以通过gsub得到你想要的：

gsub("^.* +- +([A-Za-z ]+) \\(.*$", "\\1", df$District)
[1] "North West" "North West" "North West" "North West" "North West" "North West"

gsub("^.* +- +([A-Za-z ]+) \(.*$") 的第一个参数是一个正则表达式，可以解释如下：

从字符串“^”的开头，匹配任何字符“.*”，后跟至少一个空格、一个连字符和至少一个空格“+- +”。然后捕获由（至少一个）字母和空格“[A-Za-z ]+”组成的下一个文本“()”。当您到达空格后跟括号“\\(”时停止捕获，然后匹配所有内容，直到文本“.*$”结束。

gsub 的第二个参数“\\1”表示用括号捕获的文本替换文本。

将其分配给变量：

df$name <- gsub("^.* +- +([A-Za-z ]+) \\(.*$", "\\1", df$District)

【讨论】：

@Imo：谢谢！它工作得很好。你能解释一下这是如何工作的吗？
当然可以。请参阅解释我使用的正则表达式的编辑。熟悉这个工具非常有用，因为正则表达式在软件中广泛使用。

【解决方案3】：

还可以匹配提取：

library(stringi)
library(dplyr)
library(purrr)

mutate(x,
       name=map_chr(stri_match_all_regex(District, "- ([[:alpha:]]+ [[:alpha:]]+) "), function(x) x[,2]),
       code=map_chr(stri_match_all_regex(District, "\\(([[:digit:]]+)\\)"), function(x) x[,2]))

##                     District      Age   Total  Rural   Urban       name code
## 1 District - North West (01) All ages 3656539 213950 3442589 North West   01
## 2 District - North West (01)        0   56131   3589   52542 North West   01
## 3 District - North West (01)        1   58644   3757   54887 North West   01
## 4 District - North West (01)        2   63835   4200   59635 North West   01
## 5 District - North West (01)        3   63859   4102   59757 North West   01
## 6 District - North West (01)        4   64945   4223   60722 North West   01

【讨论】：