问题
I do have a list of 53 data frames (purchase01 to purchase53), ordered by date, with 18 variables and distinct number of rows (tryed, but coulden't paste a example on the following). I want to aggregate each distinct data frame by its repeated values of "V9"- factor- by sum the column "V2"- numeric. I coulden't find the answer yet.
For only one dataframe I can use
aggregate.data.frame(purchase00$V12, by = list(purchase00($V9),FUN = sum) and itjust works fine.
I tryed llply,
llply(.data = purchase, .fun = aggregate.data.frame, by= list(unique((V9),sum, .inform = TRUE)
but without sucess, it seems that the function does not receive the by for every dataframe nor the function sum. Also the mapply didn't work well for me.
回答1:
## assuming your list is called list_of_df
require(dplyr)
summarized_list <- lapply(list_of_df, function(x) {
x %>% group_by(V9) %>% summarize(sum(V2))
})
This will return a list with the summary of each data frame in your purchase list.
If you don't want to use dplyr , you can do this with base :
lapply(list_of_df, function(x) {aggregate(values ~ day_of_week, data = x, sum) })
来源：https://stackoverflow.com/questions/40567653/r-aggregate-list-of-dataframe