R - 根据另一列中的值查找时间戳的开始和结束

Question

亲爱的，

我是R编程的新手，因此，我来这里向您寻求帮助。我正在想办法解决这个问题。我一直在努力，但没有成功。

我有一个data.frame类似的...

df2 <- data.frame(Recordig = c("Rec1", "Rec1", "Rec1", "Rec1", "Rec1", "Rec1", 
                               "Rec2","Rec2","Rec2","Rec2","Rec2","Rec2"), 
                  MediaName = c("Imagem1","Imagem1","Imagem1",
                                "Estimulo1","Estimulo1","Estimulo1",
                                "Imagem1","Imagem1","Imagem1",
                                "Estimulo1","Estimulo1","Estimulo1"),
                  Timestamp = c( 4975 , 5155 , 5312 ,25076, 25463 ,26040 , 5035 , 5248, 5551, 17047 , 17263,  17533))

下面是简化版

 Recordig MediaName Timestamp
1      Rec1   Imagem1      4975
2      Rec1   Imagem1      5155
3      Rec1   Imagem1      5312
4      Rec1 Estimulo1     25076
5      Rec1 Estimulo1     25463
6      Rec1 Estimulo1     26040
7      Rec2   Imagem1      5035
8      Rec2   Imagem1      5248
9      Rec2   Imagem1      5551
10     Rec2 Estimulo1     17047
11     Rec2 Estimulo1     17263
12     Rec2 Estimulo1     17533

我的意思是什么？我需要确切地知道参与者（例如 Rec1）在查看每张图像 (Image1) 上花费了多少时间。在这种情况下，Image1 的时间戳从 4.975 秒开始到 5.312 秒结束，给出 333 毫秒

重点是我有数百张图片和数千名受访者，他们花了不同的时间来观察这些图片。

请问有没有人能帮帮我？

Answer 1

您可以使用 dplyr 包找到每个参与者 (Recordig) 和图像 (MediaName) 的第一个和最后一个时间戳之间的差异：

library(dplyr)
df3 <- df2 %>% 
        dplyr::group_by(Recordig, MediaName) %>%
        dplyr::summarise(duration = diff(range(Timestamp)))

df3
# Source: local data frame [4 x 3]
# Groups: Recordig [?]
# 
#   Recordig MediaName duration
#     <fctr>    <fctr>    <dbl>
# 1     Rec1 Estimulo1      964
# 2     Rec1   Imagem1      337
# 3     Rec2 Estimulo1      486
# 4     Rec2   Imagem1      516

Answer 2

我们可以使用base R

aggregate(cbind(duration = Timestamp) ~Recordig + MediaName, df2,
               FUN = function(x) diff(range(x)))
#    Recordig MediaName duration
#1     Rec1 Estimulo1      964
#2     Rec2 Estimulo1      486
#3     Rec1   Imagem1      337
#4     Rec2   Imagem1      516

R - 根据另一列中的值查找时间戳的开始和结束

R - Find the begin and the end of timestamp according with values in another column

timestamp

r

data-manipulation

dataframe