如何查找一列中的文本字符串是否在另一列中？

Question

以下是样本数据

 df1 <- c ("Board of Accountancy", "Board of Economists", "Board of Medicine"
 df2 <- c ("State Board of Accountancy", "The State Board of Economists", "State Board of Law")

手头的任务有两个方面。首先，在 df2 中搜索 df1 中找到的文本字符串。如果在 df1 中没有找到它，那么就不管它并得到如下的最终结果。这与我昨天提出的一个问题有关，但经过仔细检查..我的第一项工作是查找 df1 中的名称是否在 df2 中找到。

df3: "State Board of Accountancy", "The State Board of Economists", "State Board of Law", "Board of Medicine"

Answer 1

c(df2, df1[rowSums(sapply(df1, grepl, df2)) < 1])
# [1] "State Board of Accountancy"    "The State Board of Economists" "State Board of Law"            "Board of Medicine"            
df3
# [1] "State Board of Accountancy"    "The State Board of Economists" "State Board of Law"            "Board of Medicine"            

演练：

• grepl

  本身只接受一个模式，所以我们需要迭代每个模式；我们用

  sapply

来做到这一点
• 由于 (

  sapply

  ) 返回一个矩阵（每个模式与所有

  df2

  相对应），我们需要查找一行上的任何内容（每个

  df1

  ）是否匹配；我们用

  rowSums(.) < 1

  （又名

  == 0

  ）来做到这一点，这意味着没有任何匹配；通过对

  df1[..]

  进行子集化，我们得到

  df1

  ，其中未找到匹配项

---

更正数据：

df1 <- c("Board of Accountancy", "Board of Economists", "Board of Medicine")
df2 <- c("State Board of Accountancy", "The State Board of Economists", "State Board of Law")
df3 <- c("State Board of Accountancy", "The State Board of Economists", "State Board of Law", "Board of Medicine")