使用R

Question

希望拉回一列中的值作为另一列（在同一行内）中的字符串存在的行。

我有一个df：

A <- c("cat", "dog", "boy")
B <- c("cat in the cradle", "meet the parents", "boy mmets world")

df <- as.data.frame(A, B)

A       B
cat     cat in the cradle
dog     meet the parents
boy     boy meets world

我尝试过这样的事情：

df2 <- df %>%
          filter(grepl(A, B)) # doesn't work because it thinks A is the whole column vector

df2 <- df %>%
          filter(B %in% A) # which doesn't work because it has to be exact

我希望它能够产生

A       B
cat     cat in the cradle
boy     boy meets world

提前致谢！

马特

Answer 1

我们可以使用Map

执行此操作

df[mapply(grepl, df$A, df$B),]
#    A                 B
#1 cat cat in the cradle
#3 boy   boy mmets world

更新

使用tidyverse，类似选项为purrr::map2 stringr::str_detect

library(tidyverse)
df %>% 
   filter(map2_lgl(B, A,  str_detect))
#     A                 B
#1 cat cat in the cradle
#2 boy   boy mmets world

数据

df <- data.frame(A, B, stringsAsFactors=FALSE)

Answer 2

您可以使用sapply将该函数应用于两个向量，也可以使用df %>% filter(unlist(Map(function(x, y) grepl(x, y), A, B))) A B 1 cat cat in the cradle 2 boy boy mmets world df %>% filter(sapply(1:nrow(.), function(i) grepl(A[i], B[i]))) A B 1 cat cat in the cradle 2 boy boy mmets world

遍历该行

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