问题
df1
df2
df3
library(dplyr)
library(fuzzyjoin)
df1 <- tibble(a =c("Apple Pear Orange", "Sock Shoe Hat", "Cat Mouse Dog"))
df2 <- tibble(b =c("Kiwi Lemon Apple", "Shirt Sock Glove", "Mouse Dog"),
c = c("Fruit", "Clothes", "Animals"))
# Appends 'Animals'
df3 <- regex_left_join(df1,df2, c("a" = "b"))
# Appends Nothing
df3 <- stringdist_left_join(df1, df2, by = c("a" = "b"), max_dist = 3, method = "lcs")
I want to append column c of df2 to df1 using the strings, 'Apple', 'Sock' and 'Mouse Dog'.
I tried doing this with regex_join and fuzzyjoin but the order of the string seems to matter, and can't seem to find a way around it.
回答1:
regex_left_join works, but it isn't just looking for any similarities. As it says in the description,
Join a table with a string column by a regular expression column in another table
So, we need to provide a regex pattern. If df2$b contains separate words of interest, we may do
(df2$regex <- gsub(" ", "|", df2$b))
# [1] "Kiwi|Lemon|Apple" "Shirt|Sock|Glove" "Mouse|Dog"
and then
regex_left_join(df1, df2, by = c(a = "regex"))[-ncol(df1) - ncol(df2)]
# A tibble: 3 x 3
# a b c
# <chr> <chr> <chr>
# 1 Apple Pear Orange Kiwi Lemon Apple Fruit
# 2 Sock Shoe Hat Shirt Sock Glove Clothes
# 3 Cat Mouse Dog Mouse Dog Animals
where -ncol(df1) - ncol(df2) simply drops the last column containing the regex patterns.
来源：https://stackoverflow.com/questions/54079535/r-regex-join-fuzzy-join-join-inexact-strings-in-different-word-orders