Question

假设我有一些词根，前缀和后缀。

roots <- c("car insurance", "auto insurance")
prefix <- c("cheap", "budget")
suffix <- c("quote", "quotes")

R中是否有一个简单的函数或包可以构造三个特征向量的所有可能组合。

所以我想要一个返回以下列表的列表，数据框或向量每个字符串的所有可能组合。

cheap car insurance
budget car insurance
cheap car insurance quotes
cheap auto insurance quotes
auto insurance quote
auto insurance quotes
...

像“汽车保险报价”这样的东西，我只使用后缀而没有前缀，所以我需要得到这些结果的所有可能结果。

Answer 1

expand.grid是你的朋友：

expand.grid(prefix, roots, suffix)

    Var1           Var2   Var3
1  cheap  car insurance  quote
2 budget  car insurance  quote
3  cheap auto insurance  quote
4 budget auto insurance  quote
5  cheap  car insurance quotes
6 budget  car insurance quotes
7  cheap auto insurance quotes
8 budget auto insurance quotes

编辑包含Prasad的有用评论：

但是，您会注意到结果是因素而不是字符。要将这些因素转换为字符向量，您可以使用do.call和paste，如下所示：

do.call(paste, expand.grid(prefix, roots, suffix))

[1] "cheap car insurance quote"    "budget car insurance quote"  
[3] "cheap auto insurance quote"   "budget auto insurance quote" 
[5] "cheap car insurance quotes"   "budget car insurance quotes" 
[7] "cheap auto insurance quotes"  "budget auto insurance quotes"

Answer 2

您可以使用paste函数作为outer的参数：

outer(prefix,outer(roots,suffix,paste),paste)

输出：

, , 1

     [,1]                         [,2]                         
[1,] "cheap car insurance quote"  "cheap auto insurance quote" 
[2,] "budget car insurance quote" "budget auto insurance quote"

, , 2

     [,1]                          [,2]                          
[1,] "cheap car insurance quotes"  "cheap auto insurance quotes" 
[2,] "budget car insurance quotes" "budget auto insurance quotes"

可以使用as.vector将其缩小为单个矢量。

查找三个字符串的所有可能组合

2 个答案: