如何从 R 中的字符串中的多个列表中检测子字符串

Question

我正在尝试查找名为 "values" 的字符串是否包含来自两个不同列表的子字符串。这是我当前的代码：

for (i in 1:length(value)){
  for (j in 1:length(city)){
    if (str_detect(value[i],(city[j]))) == TRUE){
        for (k in 1:length(school)){
            if (str_detect(value[i],(school[j]))) == TRUE){
        ...........................................................
        }
      }
    }
  }
}

city 和 school 是不同长度的独立向量，每个向量都包含字符串元素。

city <- ("Madrid", "London", "Paris", "Sofia", "Cairo", "Detroit", "New York")
school <- ("Law", "Mathematics", "PoliSci", "Economics")
value <- ("Rey Juan Carlos Law Dept, Madrid", "New York University, Center of PoliSci Studies", ..........)

我想做的是查看 value 是否包含两个列表中元素的某种组合，以便稍后使用。这可以一步完成吗：像这样：

for (i in 1:length(value)){
    if (str_detect(value[i],(city[j]))) == TRUE && str_detect(value[i],(school[j]))) == TRUE){
                   .............................................
    }
}

Answer 1

试试这个：

library("stringr")

city <- c("Madrid", "London", "Paris", "Sofia", "Cairo", "Detroit", "New York")
school <- c("Law", "Mathematics", "PoliSci", "Economics")
value <- c(
  "Rey Juan Carlos Law Dept, Madrid",
  "New York University, Center of PoliSci Studies",
  "Los Angeles, CALTECH",
  "London, Physics",
  "London, Mathematics"
      )

for (v in value)
{
  if (sum(str_detect(v, city)) > 0 & sum(str_detect(v, school)) > 0)
  {
    print (v)
  }
}

执行时将打印与城市和学校有共同元素的那些：

[1] "Rey Juan Carlos Law Dept, Madrid"
[1] "New York University, Center of PoliSci Studies"
[1] "London, Mathematics"

Answer 2

这个问题与我一直在处理的问题类似。出于我的目的，需要返回一个保留原始输入结构的数据框。

这对你来说可能也是如此。因此，我修改了@rbm 的优秀解决方案如下：

library("stringr")

cityList <- c("Madrid", "London", "Paris", "Sofia", "Cairo", "Detroit", "New York")
schoolList <- c("Law", "Mathematics", "PoliSci", "Economics")
valueList <- c(
  "Rey Juan Carlos Law Dept, Madrid",
  "New York University, Center of PoliSci Studies",
  "Los Angeles, CALTECH",
  "London, Physics",
  "London, Mathematics"
)


df <- data.frame(value, city=NA, school=NA, stringsAsFactors = FALSE)

i = 0
for (v in value)
{
  i = i + 1
  if (sum(str_detect(v, cityList)) > 0 & sum(str_detect(v, schoolList)) > 0)
  {
    df$city[i] <- schoolList[[which(str_detect(v, schoolList))]]
    df$school[i] <- cityList[[which(str_detect(v, cityList))]]
  } else {
    df$city[i] <- ""
    df$school[i] <- ""
  }
}
print(df)

结果如下：

                                          value        city   school
1               Rey Juan Carlos Law Dept, Madrid         Law   Madrid
2 New York University, Center of PoliSci Studies     PoliSci New York
3                           Los Angeles, CALTECH                     
4                                London, Physics                     
5                            London, Mathematics Mathematics   London

如何从 R 中的字符串中的多个列表中检测子字符串

How to detect substrings from multiple lists within a string in R

r

string-matching

nested-loops

stringr