我要left_join
多个数据框:
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
之所以可行b
,是因为它们都具有相同的列,但Reduce
不允许我指定其他可以传递给的参数left_join
。是否可以解决类似这样的问题?
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"))
)
更新资料
这种工作方式:Reduce(function(...) left_join(..., by = c("b" = "d")), dfs)
但是当by
一个以上元素时,会出现此错误:Error: cannot join on columns 'b' x 'd': index out of bounds
我知道为时已晚。...今天我被介绍到未回答的问题部分。很抱歉打扰。
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 8
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