r - 合并奇数个带后缀的数据帧
问题描述
我正在尝试合并数据框列表,并且在这个社区中遇到了许多不同的答案,例如R-reduce with merge 和超过 2 个后缀(或:如何合并多个数据框并跟踪列)。但是在解决了这些答案之后,它适用于偶数个数据帧,但不适用于奇数个数据帧。
myDF <- cbind(typecar = rownames(mtcars), mtcars)
rownames(myDF) <- NULL
df1 <- myDF
df2 <- myDF
df3<- myDF
df4 <- myDF
for(i in head(seq_along(list.df), -1)) {
res <- merge(res, list.df[[i+1]], all = TRUE,
suffixes = sfx[i:(i+1)], by = "typecar")
}
这里上面的代码对偶数个df按预期工作,如下所示
list.df <- list(df1, df2, df3,df4)
sfx <- c(".df1", ".df2", ".df3", ".df4")
但是在尝试奇数时,最后一个 .df3 不会作为后缀添加
list.df <- list(df1, df2, df3)
sfx <- c(".df1", ".df2", ".df3")
这里的 colnames 看起来像这样。
[1] "typecar" "mpg.df1" "cyl.df1" "disp.df1" "hp.df1" "drat.df1" "wt.df1" "qsec.df1" "vs.df1" "am.df1" "gear.df1" "carb.df1" "mpg.df2"
[14] "cyl.df2" "disp.df2" "hp.df2" "drat.df2" "wt.df2" "qsec.df2" "vs.df2" "am.df2" "gear.df2" "carb.df2" "mpg" "cyl" "disp"
[27] "hp" "drat" "wt" "qsec" "vs" "am" "gear" "carb"
我想要的是
[1] "typecar" "mpg.df1" "cyl.df1" "disp.df1" "hp.df1" "drat.df1" "wt.df1" "qsec.df1" "vs.df1" "am.df1" "gear.df1" "carb.df1" "mpg.df2"
[14] "cyl.df2" "disp.df2" "hp.df2" "drat.df2" "wt.df2" "qsec.df2" "vs.df2" "am.df2" "gear.df2" "carb.df2" "mpg.df3" "cyl.df3" "disp.df3"
[27] "hp.df3" "drat.df3" "wt.df3" "qsec.df3" "vs.df3" "am.df3" "gear.df3" "carb.df3"
尝试使用 dplyr join 但情况相同。遇到了这个https://github.com/tidyverse/dplyr/issues/1296。有什么方法可以处理奇数个数据帧吗?
解决方案
一个更简单的选择是list
使用相应的list
名称或对象名称作为后缀命名元素列名称,但by
在merge
.
list.df <- Map(function(x, nm) {i1 <- names(x) != 'typecar'
names(x)[i1] <- paste0(names(x)[i1], ".", nm)
x
}, list.df, names(list.df))
然后,我们利用Reduce/merge
out <- Reduce(function(...) merge(..., by = 'typecar', all = TRUE), list.df)
names(out)
#[1] "typecar" "mpg.df1" "cyl.df1" "disp.df1" "hp.df1" "drat.df1" "wt.df1" "qsec.df1" "vs.df1" "am.df1" "gear.df1" "carb.df1"
#[13] "mpg.df2" "cyl.df2" "disp.df2" "hp.df2" "drat.df2" "wt.df2" "qsec.df2" "vs.df2" "am.df2" "gear.df2" "carb.df2" "mpg.df3"
#[25] "cyl.df3" "disp.df3" "hp.df3" "drat.df3" "wt.df3" "qsec.df3" "vs.df3" "am.df3" "gear.df3" "carb.df3"
数据
list.df <- mget(paste0('df', 1:3))
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