如何在dplyr中正確設置排列和分組？

Question

我的數據結構如下：

Athletes = c("Gus", "Hudson", "Bobby", "Tom") 
set.seed(400) 
RawData <- data.frame(Name = rep((Athletes), each = 400), 
           Quarter = as.numeric(rep(1:4, each = 100)), 
           Sample = as.numeric(rep(1:100, each = 1)), 
           X = runif(400, 26, 30), 
           Y = runif(400, 12, 16)) 

祝在每個Sample每Quarter來計算位移，每個X和Y對，對於每個Athlete。要做到這一點，我已經安裝了下面的代碼：

DistanceOutput <- RawData %>% 
    arrange(Name, Sample, Quarter) %>% 
    group_by(Name, Quarter) %>% 
    mutate(lagX = lag(X, order_by=Sample), lagY = lag(Y, order_by=Sample)) %>% 
    rowwise() %>% 
    mutate(Distance = dist(matrix(c(X,Y,lagX,lagY),nrow=2,byrow=TRUE))) %>% 
    select(-lagX, -lagY) 

然而，這會返回一個data.frame該結構如下：

> head(DistanceOutput, n=10) 
Source: local data frame [10 x 6] 

    Name Quarter Sample  X  Y Distance 
    (fctr) (dbl) (dbl) (dbl) (dbl) (dbl) 
1 Bobby  1  1 27.82656 13.85830  NA 
2 Bobby  2  1 27.37298 15.67940  NA 
3 Bobby  3  1 28.74274 12.25703  NA 
4 Bobby  4  1 26.63564 13.07924  NA 
5 Bobby  1  2 26.32446 12.64722 1.929508 
6 Bobby  2  2 26.88957 14.52096  NA 
7 Bobby  3  2 27.53932 15.57959 3.533781 
8 Bobby  4  2 28.03031 12.70763 1.443328 
9 Bobby  1  3 29.68239 13.82739 3.559287 
10 Bobby  2  3 29.43869 12.60890 3.186531 

相反，我寧願我的數據是設置如下：

> head(DistanceOutput, n=3) 
    Source: local data frame [10 x 6] 

     Name Quarter Sample  X  Y Distance 
     (fctr) (dbl) (dbl) (dbl) (dbl) (dbl) 
    1 Bobby  1  1 27.82656 13.85830  NA 
    2 Bobby  1  2 26.32446 12.64722 1.929508 
    3 Bobby  1  3 29.68239 13.82739 3.559287 

我怎麼正確設置GROUP_BY並安排內dplyr陳述，以正確反映我期望的輸出？

謝謝。

Answer 1

我想這是我沒有包含`set.seed`訂單問題

DistanceOutput %>% 
     arrange(Name, Quarter, Sample) %>% 
     head(3) 
# Name Quarter Sample  X  Y Distance 
# <fctr> <dbl> <dbl> <dbl> <dbl> <dbl> 
#1 Bobby  1  1 28.40293 15.40195  NA 
#2 Bobby  1  2 26.33676 14.32382 2.330544 
#3 Bobby  1  3 28.60779 14.67457 2.297951