如何从R中的字符串中的多个列表中检测子字符串答案

【问题标题】：How to detect substrings from multiple lists within a string in R如何从R中的字符串中的多个列表中检测子字符串
【发布时间】：2015-09-22 10:49:18
【问题描述】：

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", ..........)

我想要做的是查看value 是否包含两个列表中的某些元素组合，以便以后使用。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){
                   .............................................
    }
}

【问题讨论】：

你能举一些值的例子吗
我在上面的问题中举了一些例子

标签： r nested-loops string-matching stringr

【解决方案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)
  }
}

当执行时，它会打印出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"

【讨论】：

【解决方案2】：

这个问题与我一直在研究的类似。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正确的。因此，我将@rbm 的优秀解决方案修改如下：

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)

这会导致以下结果：

                                          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

【讨论】：