如何使用dplyr连接多个数据帧？
如何使用dplyr连接多个数据帧？
提问于 2015-12-17 21:04:53
我想要left_join多个数据帧：
dfs <- list(
df1 = data.frame(a = 1:3, b = c("a", "b", "c")),
df2 = data.frame(c = 4:6, b = c("a", "c", "d")),
df3 = data.frame(d = 7:9, b = c("b", "c", "e"))
)
Reduce(left_join, dfs)
# a b c d
# 1 1 a 4 NA
# 2 2 b NA 7
# 3 3 c 5 8这是因为它们都有相同的b列，但是Reduce不允许我指定可以传递给left_join的其他参数。有这样的工作吗？
dfs <- list(
df1 = data.frame(a = 1:3, b = c("a", "b", "c")),
df2 = data.frame(c = 4:6, d = c("a", "c", "d")),
df3 = data.frame(d = 7:9, b = c("b", "c", "e"))
)更新
这类工作：Reduce(function(...) left_join(..., by = c("b" = "d")), dfs)，但是当by是多个元素时，它会给出这样的错误：Error: cannot join on columns 'b' x 'd': index out of bounds
回答 3
Stack Overflow用户
回答已采纳
发布于 2016-12-03 07:20:13
已经太晚了，我know....today我被介绍到未回答的问题部分。抱歉打扰了。
使用left_join()
dfs <- list(
df1 = data.frame(b = c("a", "b", "c"), a = 1:3),
df2 = data.frame(d = c("a", "c", "d"), c = 4:6),
df3 = data.frame(b = c("b", "c", "e"), d = 7:9)
)
func <- function(...){
df1 = list(...)[[1]]
df2 = list(...)[[2]]
col1 = colnames(df1)[1]
col2 = colnames(df2)[1]
xxx = left_join(..., by = setNames(col2,col1))
return(xxx)
}
Reduce( func, dfs)
# b a c d
#1 a 1 4 NA
#2 b 2 NA 7
#3 c 3 5 8使用merge()：
func <- function(...){
df1 = list(...)[[1]]
df2 = list(...)[[2]]
col1 = colnames(df1)[1]
col2 = colnames(df2)[1]
xxx=merge(..., by.x = col1, by.y = col2, , all.x = T)
return(xxx)
}
Reduce( func, dfs)
# b a c d
#1 a 1 4 NA
#2 b 2 NA 7
#3 c 3 5 8Stack Overflow用户
发布于 2015-12-17 21:24:17
这对你有用吗？
jnd.tbl <- df1 %>%
left_join(df2, by='b') %>%
left_join(df3, by='d')Stack Overflow用户
发布于 2022-02-11 14:15:41
另一个解决办法是：
library(purrr)
library(dplyr)
dfs = list(
df1 = data.frame(a = 1:3, b = c("a", "b", "c")),
df2 = data.frame(c = 4:6, b = c("a", "c", "d")),
df3 = data.frame(d = 7:9, b = c("b", "c", "e"))
)
purrr::reduce(dfs, dplyr::left_join, by = 'b')页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/34344214
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