R dataframe 按因子拆分然后应用和 tidyr

Question

有 8 周的互联网实验。收集每个参与者的数据，他们可以在任何日期开始实验。这个想法是计算每个参与者在第一周、第二周等所做的练习。所以结果应该是参与者乘以 8 matrix/data 帧。

每个参与者可以在任何日期开始，但实验在 8 周后结束
每个参与者都可以做 he/she 想做的练习。

举个例子

df <- data.frame(
        fac=c("a","a","a","a","a","b","b","b","b","b","c","c","c","c","c","d","d","d","d","d","d"), 
        date=c("2017-01-01","2017-01-05","2017-01-13","2017-01-25","2017-02-10","2017-01-06","2017-01-16","2017-01-28","2017-02-02","2017-02-07","2017-01-11","2017-01-19","2017-01-24","2017-01-31","2017-02-09","2017-01-12","2017-01-24","2017-01-29","2017-02-04","2017-02-19","2017-03-08"), 
        sessions=c(1,2,3,6,5,1,3,2,3,3,1,5,3,2,4,1,3,5,2,6,6)
        )

我的想法是：

添加“0”列 (df$count<-0)
按因子拆分数据框 [split(df, df$fac)] 3
取日期值-减去第一个条目的日期值，加1，除以7，然后向上取整。 [综述（（date2 -date$1$+1）/7）]。这给了我参与者做练习的确切周数。
使用 tidyr：重组整个数据框，以便将每周的值相加（参与者乘以 8 个数据框）

但我不知道如何正确执行步骤 3 以及如何与步骤 4 结合

非常感谢！

Answer 1

类似于：

library(dplyr)
df <- df %>% 
    group_by(fac) %>% 
    mutate(time = ceiling(1+difftime(as.Date(date), as.Date(date[1]), units = 'weeks')))
summarize(df, total_sessions = sum(sessions))

R dataframe 按因子拆分然后应用和 tidyr

R dataframe split by factor then apply and tidyr

split

r

apply

dataframe

tidyr