我有一个包含9个数据帧的列表,每个数据帧有大约100行和5-6列。
我希望根据所有数据框中另一个col中指定的组聚合col中的值,并将所有结果存储在单独的数据框中。为了阐明,请考虑一个列表
[[1]]
Date Group Age
Nov A 13
Nov A 14
Nov B 9
Nov D 10
[[2]]
Date Group Age
Dec C 11
Dec C 12
Dec E 10
我的代码如下
for (i in 1:length(list)){
x<-aggregate(list[[i]]$Age~list[[i]]$Group, list[[i]], sum)
x<-rbind(x)
}
但最后,x只包含数据帧2的聚合结果(因为i = 2)而不包含数据帧1的聚合结果,尽管我试图绑定结果。
非常感谢任何帮助。
答案 0 :(得分:1)
In R, there are many efficiently implemented function which help to avoid the hassle of writing for
loops.
In his comment, S Rivero has suggested to use lapply()
instead of a for
loop and to rbind()
the aggregates later:
do.call(rbind, lapply(dflist, function(x) aggregate(Age ~ Group, x, sum)))
My suggestion is, to combine the data.frames first and then to compute the aggregates using data.table
:
library(data.table)
rbindlist(dflist)[, sum(Age), by = Group]
Group V1 1: A 27 2: B 9 3: D 10 4: C 23 5: E 10
dflist <- list(structure(list(Date = c("Nov", "Nov", "Nov", "Nov"), Group = c("A",
"A", "B", "D"), Age = c(13L, 14L, 9L, 10L)), .Names = c("Date",
"Group", "Age"), row.names = c(NA, -4L), class = "data.frame"),
structure(list(Date = c("Dec", "Dec", "Dec"), Group = c("C",
"C", "E"), Age = c(11L, 12L, 10L)), .Names = c("Date", "Group",
"Age"), row.names = c(NA, -3L), class = "data.frame"))