For循環以子集數據幀列表

Question

我有一個數據框列表：

df1<-data.frame("A"=1:10, "B"=c("Mark","John","Lucas","Helen","Rachel","Leyla","Tina","Fanny","Emma","Kate"),"C"=c(91:100))
df2<-data.frame("A"=1:8, "B"=c("Mark","John","Lucas","Helen","Rachel","Leyla","Tina","Fanny"),"C"=c(93:100))
df3<-data.frame("A"=1:3, "B"=c("Mark","John","Lucas"),"C"=c(98:100))
all_df<-list(df1,df2,df3)

我想創建一個按列子集的數據框的新列表，如下所示：

df1_sub<-df1[,c("B","C")]
df2_sub<-df1[,c("B","C")]
df3_sub<-df1[,c("B","C")]
all_df_sub<-list(df1_sub,df2_sub,df3_sub)

最后為每個新的 dataframe 分配其名稱：

mynames<-c("df1_sub","df2_sub","df3_sub")
names(all_df_sub)<-mynames

我想使用lapply和for循環來做到這一點，但我無法弄清楚如何，因為我在定義 function 和子集數據幀列表之間的某個地方陷入困境（我對此不是很有信心，我檢查了較舊的類似沒有成功的問題）。 到目前為止，這是我正在嘗試的：

all_df_sub<-lapply(all_df, function(all_df){
  for([[i]] in all_df) {
    a<-[[i]][,c("B","C")]
    } 
  all_df } )

任何建議將不勝感激。 謝謝！

Answer 1

你可以試試這個：

all_df_sub <-lapply(all_df, function(dat){dat[2:3]})
all_df_sub <-setNames(all_df_sub, c("df1_sub","df2_sub","df3_sub"))