list 我可以将一系列相似的数据帧合并到一个数据帧中吗？
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Can I combine a list of similar dataframes into a single dataframe?
提问by David LeBauer
I have a dataframe:
我有一个数据框：
foo <- list(df1 = data.frame(x=c('a', 'b', 'c'),y = c(1,2,3)),
df2 = data.frame(x=c('d', 'e', 'f'),y = c(4,5,6)))
Can I convert it to a single dataframe of the form:
我可以将其转换为以下形式的单个数据帧：
data.frame(x = c('a', 'b', 'c', 'd', 'e', 'f'), y= c(1,2,3,4,5,6))
?
?
回答by Hong Ooi
do.call("rbind", foo)should do the trick.
do.call("rbind", foo)应该做的伎俩。
回答by Sacha Epskamp
with plyr:
与plyr：
foo <- list(df1 = data.frame(x=c('a', 'b', 'c'),y = c(1,2,3)),
df2 = data.frame(x=c('d', 'e', 'f'),y = c(4,5,6)))
library(plyr)
ldply(foo)[,-1]
x y
1 a 1
2 b 2
3 c 3
4 d 4
5 e 5
6 f 6
回答by Andrie
There are several problems with your code.
您的代码有几个问题。
The first is that the assignment statement in the list doesn't work. This needs to be fixed by, for example:
首先是列表中的赋值语句不起作用。这需要修复，例如：
foo <- list(
df1 = data.frame(x=c('a', 'b', 'c'), y = c(1,2,3)),
df2 = data.frame(x=c('d', 'e', 'f'), y = c(4,5,6))
)
You can then use rbind() to combine the data frames:
然后您可以使用 rbind() 组合数据框：
rbind(foo$df1, foo$df2)
x y
1 a 1
2 b 2
3 c 3
4 d 4
5 e 5
6 f 6
But this poses more questions. For example, why do you combine the data frames in a list in the first place. The second is whether you really need to use data frames rather than vectors. Finally, I generally try to avoid rbind() and rather use merge() when combining data frames in this way.
但这带来了更多的问题。例如，为什么首先将列表中的数据框组合在一起。第二个是你是否真的需要使用数据框而不是向量。最后，在以这种方式组合数据帧时，我通常会尽量避免 rbind() 而是使用 merge() 。
回答by Chase
How about merge(foo[[1]], foo[[2]], all = TRUE)
怎么样 merge(foo[[1]], foo[[2]], all = TRUE)
