r - 传播与 dcast

Question

我有一张这样的 table ，

> head(dt2)
  Weight Height   Fitted interval limit    value
1   65.6  174.0 71.91200     pred   lwr 53.73165
2   80.7  193.5 91.63237     pred   lwr 73.33198
3   72.6  186.5 84.55326     pred   lwr 66.31751
4   78.8  187.2 85.26117     pred   lwr 67.02004
5   74.8  181.5 79.49675     pred   lwr 61.29244
6   86.4  184.0 82.02501     pred   lwr 63.80652

我希望它有这样的，

> head(reshape2::dcast(dt2, 
         Weight + Height + Fitted + interval ~ limit, 
         fun.aggregate = mean))
  Weight Height   Fitted interval      lwr      upr
1   42.0  153.4 51.07920     conf 49.15463 53.00376
2   42.0  153.4 51.07920     pred 32.82122 69.33717
3   43.2  160.0 57.75378     conf 56.35240 59.15516
4   43.2  160.0 57.75378     pred 39.54352 75.96404
5   44.8  149.5 47.13512     conf 44.87642 49.39382
6   44.8  149.5 47.13512     pred 28.83891 65.43133

但是使用 tidyr::spread ， 我怎样才能做到这一点？

我正在使用，

> tidyr::spread(dt2, limit, value)

但得到错误，

Error: Duplicate identifiers for rows (1052, 1056), (238, 242), (1209, 1218), (395, 404), (839, 1170), (25, 356), (1173, 1203, 1215), (359, 389, 401), (1001, 1200), (187, 386), (906, 907), (92, 93), (930, 1144), (116, 330), (958, 1171), (144, 357), (902, 1018), (88, 204), (960, 1008), (146, 194), (1459, 1463), (645, 649), (1616, 1625), (802, 811), (1246, 1577), (432, 763), (1580, 1610, 1622), (766, 796, 808), (1408, 1607), (594, 793), (1313, 1314), (499, 500), (1337, 1551), (523, 737), (1365, 1578), (551, 764), (1309, 1425), (495, 611), (1367, 1415), (553, 601)

随机 10 行::

> dt[sample(nrow(dt), 10), ]
     Weight Height   Fitted interval limit    value
1253   52.2  162.5 60.28203     conf   upr 61.51087
426    49.1  158.8 56.54022     pred   upr 74.75756
1117   78.4  184.5 82.53066     conf   lwr 80.98778
1171   85.9  166.4 64.22611     conf   lwr 63.21254
948    61.4  177.8 75.75494     conf   lwr 74.66393
384    90.9  172.7 70.59731     pred   lwr 52.41828
289    75.9  172.7 70.59731     pred   lwr 52.41828
3      44.8  149.5 47.13512     pred   lwr 28.83891
774    87.3  182.9 80.91258     pred   upr 99.12445
772    86.4  175.3 73.22669     pred   upr 91.40919

Answer 1

假设您从如下所示的数据开始:

mydf
#   Weight Height  Fitted interval limit    value
# 1     42  153.4 51.0792     conf   lwr 49.15463
# 2     42  153.4 51.0792     pred   lwr 32.82122
# 3     42  153.4 51.0792     conf   upr 53.00376
# 4     42  153.4 51.0792     pred   upr 69.33717
# 5     42  153.4 51.0792     conf   lwr 60.00000
# 6     42  153.4 51.0792     pred   lwr 90.00000

请注意分组列(1 到 5)的第 5 行和第 6 行中的重复项。这基本上就是“tidyr”告诉你的。第一行和第五行是重复的，第二行和第六行也是如此。

tidyr::spread(mydf, limit, value)
# Error: Duplicate identifiers for rows (1, 5), (2, 6)

正如@Jaap 所建议的，解决方案是首先“总结”数据。由于“tidyr”仅用于整形数据(与聚合和整形的“reshape2”不同)，您需要在更改数据形式之前使用“dplyr”执行聚合。在这里，我用 summarise 做到了。对于“值”列。

如果您在 summarise 处停止执行一步，你会发现我们原来的 6 行数据集已经“缩小”到 4 行。现在， spread会按预期工作。

mydf %>% 
  group_by(Weight, Height, Fitted, interval, limit) %>% 
  summarise(value = mean(value)) %>% 
  spread(limit, value)
# Source: local data frame [2 x 6]
# 
#   Weight Height  Fitted interval      lwr      upr
#    (dbl)  (dbl)   (dbl)    (chr)    (dbl)    (dbl)
# 1     42  153.4 51.0792     conf 54.57731 53.00376
# 2     42  153.4 51.0792     pred 61.41061 69.33717

这与 dcast 的预期输出相匹配与 fun.aggregate = mean .

reshape2::dcast(mydf, Weight + Height + Fitted + interval ~ limit, fun.aggregate = mean)
#   Weight Height  Fitted interval      lwr      upr
# 1     42  153.4 51.0792     conf 54.57731 53.00376
# 2     42  153.4 51.0792     pred 61.41061 69.33717

样本数据:

 mydf <- structure(list(Weight = c(42, 42, 42, 42, 42, 42), Height = c(153.4, 
     153.4, 153.4, 153.4, 153.4, 153.4), Fitted = c(51.0792, 51.0792,         
     51.0792, 51.0792, 51.0792, 51.0792), interval = c("conf", "pred",        
     "conf", "pred", "conf", "pred"), limit = structure(c(1L, 1L,             
     2L, 2L, 1L, 1L), .Label = c("lwr", "upr"), class = "factor"),            
         value = c(49.15463, 32.82122, 53.00376, 69.33717, 60,          
         90)), .Names = c("Weight", "Height", "Fitted", "interval",     
     "limit", "value"), row.names = c(NA, 6L), class = "data.frame")