如何在R中使用dplyr :: inner_join多个tbls或data.frames

Question

在R中，我如何有效地inner_join多个tbls或data.frame？

例如：

devtools::install_github("rstudio/EDAWR")
library(EDAWR)
library(dplyr)
data(songs)
data(artists)
test <- songs
colnames(test) <- c("song2", "name")
inner_join(songs, artists,by="name") %>% inner_join(test,by="name")

我想要加入数百test个data.frames。

Answer 1

您可以在列表中收集数据框并使用Reduce：

L <- list(songs, artists, test)
Reduce(inner_join, L)

#   name  plays                song               song2
# 1 John guitar Across the Universe Across the Universe
# 2 John guitar       Come Together Across the Universe
# 3 John guitar Across the Universe       Come Together
# 4 John guitar       Come Together       Come Together
# 5 Paul   bass      Hello, Goodbye      Hello, Goodbye

您可以使用L <- mget(ls())（可选pattern arg到ls）将所有内容放入列表中。

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正如@akrun在评论中提到的，plyr替代方案是：

library(plyr)
join_all(L, type='inner')