获取匹配的字符串？

Question

我有两个数据框，一个有产品名称，另一个有类别。现在我需要将类别与产品名称匹配，如果字符串匹配，则将相应的类别分配给名称。

所以包含产品名称 (Product_Name.csv) 的第一个数据框是：

           **Product.Name**
       Black Printed Blouse
Silver Embellished Crop Top
   Maroon Solid Strappy Top

包含类别的另一个数据框（Category.csv）是：

**Category**
     Strappy
      Blouse
        Crop 

最终输出应该是：

       Black Printed Blouse       Blouse
Silver Embellished Crop Top         Crop
   Maroon Solid Strappy Top      Strappy

现在，我正在使用 grepl，它给出真假

product <- read.csv("Product_Name.csv", header = T, sep = ",")
category <- read.csv("Category.csv", header = T, sep = ",")


for (i in 1:nrow(product)){

product[i, 2] <- grepl(Category$Category[1], product$Product.Name[i], ignore.case = TRUE)
product[i, 3] <- grepl(Category$Category[2], product$Product.Name[i], ignore.case = TRUE)
product[i, 4] <- grepl(Category$Category[3], product$Product.Name[i], ignore.case = TRUE)


}

Answer 1

我们可以使用str_extract

library(stringr)
product$Category <- str_extract(product$Product.Name, paste(category$Category, collapse="|"))
product
#                 Product.Name Category
#1        Black Printed Blouse   Blouse
#2 Silver Embellished Crop Top     Crop
#3    Maroon Solid Strappy Top  Strappy

Answer 2

使用基础 - R

indices = sapply(category$Category, function(x) which(grepl(x, product$Product.Name)))

product$new_col = 1:nrow(product)
product$new_col[indices] = names(indices)
#> df
#            X..Product.Name.. new_col
#1        Black Printed Blouse  Blouse
#2 Silver Embellished Crop Top    Crop
#3    Maroon Solid Strappy Top Strappy

---

# incase of any no-match cases(which we need to handle well)
# below code manages both well (a generalised version)

category$Category[2] = "Bloiuse"

indices = sapply(category$Category, function(x) which(grepl(x, product$Product.Name)))
indices.loc <- as.numeric(indices)
indices.name <- names(indices)

product$new_col[indices.loc[!is.na(indices.loc)]] = indices.name[!is.na(indices.loc)]

#> product
#                 Product.Name new_col
#1        Black Printed Blouse    <NA>
#2 Silver Embellished Crop Top    Crop
#3    Maroon Solid Strappy Top Strappy