R用cut()显示空组

时间:2017-06-30 09:21:15

标签: r data.table

我有一组数据:

   Abweichung BW_Gesamt
76        236   1137747
77       2000   1149019
78       2000   1227972
79       2331   1346480
80       4000   2226810
81       5272   2874114
82       8585   4418070
83      15307   5389585

现在我想把它们分组。困难在于我可以通过输入x轴的MIN / MAX和组的数量来应用灵活的中断。因此,它会将数据切割成“MYSCHRTW”宽的组:

bins <- 4 # Amount of groups
MYMIN <- 0
MYMAX <- 20000
MYSCHRTW <- (-MYMIN+MYMAX)%/%bins # Wide of one group 5000
GRENZEN <- seq(from = MYMIN, by = MYSCHRTW, length.out = bins)
GRENZEN <- c(GRENZEN, MYMAX+1) #Brakes: 0 5000 10000 15000 20001

我使用剪切功能:

setDT(mydata)[ , Gruppen := cut(mydata$Abweichung,breaks=GRENZEN,dig.lab = 5)]

问题是,缺少一个组,因为它是空的,因此没有显示。在没有该组的情况下绘制数据会使结果产生偏差 那么如何添加组(10000,15000),与Abweichung和BW_Gesamt 0:

   Abweichung BW_Gesamt       Gruppen
1:        236   1137747      (0,5000]
2:       2000   1149019      (0,5000]
3:       2000   1227972      (0,5000]
4:       2331   1346480      (0,5000]
5:       4000   2226810      (0,5000]
6:       5272   2874114  (5000,10000]
7:       8585   4418070  (5000,10000]
8:      15307   5389585 (15000,20001]

2 个答案:

答案 0 :(得分:1)

好的,我不知道它是否有效但有办法:

library(data.table)

您使用的数据:

mydata <- data.table(Abweichung = c(236,2000,2000,2331,4000,5272,8585,15307),
                     BW_Gesamt = c(1137747,1149019,1227972,1346480,2226810,2874114,4418070,5389585))


> mydata
   Abweichung BW_Gesamt
1:        236   1137747
2:       2000   1149019
3:       2000   1227972
4:       2331   1346480
5:       4000   2226810
6:       5272   2874114
7:       8585   4418070
8:      15307   5389585

首先创建一个data.table,其中包含cut()中的所有群组:

groups_cut <- data.table(Gruppen = levels(cut(mydata[, Abweichung],breaks=GRENZEN,dig.lab = 5)))

> groups_cut
         Gruppen
1:      (0,5000]
2:  (5000,10000]
3: (10000,15000]
4: (15000,20001]

然后是第二个data.table,您可以在其中计算变量Gruppen的出现次数:

mydata <- mydata[ , Gruppen := cut(mydata[, Abweichung],breaks=GRENZEN,dig.lab = 5)][, .N, by = Gruppen]

         Gruppen N
1:      (0,5000] 5
2:  (5000,10000] 2
3: (15000,20001] 1

现在您可以合并两个data.table

merge_dt<- mydata[groups_cut, on = "Gruppen"]

> merge_dt
         Gruppen  N
1:      (0,5000]  5
2:  (5000,10000]  2
3: (10000,15000] NA
4: (15000,20001]  1

如果您不想保留NA值,可以在合并后添加一些语法:

merge_dt <- mydata[groups_cut, on = "Gruppen"][, N := replace(N, is.na(N), 0)]

> merge_dt
         Gruppen N
1:      (0,5000] 5
2:  (5000,10000] 2
3: (10000,15000] 0
4: (15000,20001] 1

答案 1 :(得分:1)

我想我自己找到了答案: 所以继续我的初始职位:

setDT(mydata)[ , Gruppen := cut(mydata$Abweichung,breaks=GRENZEN,dig.lab = 5)]
> print(mydata)
   Abweichung BW_Gesamt       Gruppen
1:        236   1137747      (0,5000]
2:       2000   1149019      (0,5000]
3:       2000   1227972      (0,5000]
4:       2331   1346480      (0,5000]
5:       4000   2226810      (0,5000]
6:       5272   2874114  (5000,10000]
7:       8585   4418070  (5000,10000]
8:      15307   5389585 (15000,20000]

> class(mydata$Abweichung)
[1] "numeric"
> class(mydata$BW_Gesamt)
[1] "numeric"

library(dplyr)

mydata <- levels(mydata$Gruppen) %>%  #get distinct levels of the Gruppen variable
  data.frame(Gruppen = .) %>%  # create a data frame
  left_join(mydata %>%    # join with
              group_by(Gruppen) %>%    # for each value that exists
              summarise(Abweichung = n(), BW_Gesamt = sum(BW_Gesamt)), by = "Gruppen") %>%      # get occurrence of Abweichung and sum of BW_Gesamt just for fun 
  mutate(Abweichung = coalesce(Abweichung, 0L)) %>%  # replace NAs with 0s
  mutate(BW_Gesamt = coalesce(as.integer(BW_Gesamt), 0L))

> class(mydata$Abweichung)
[1] "integer"
> class(mydata$BW_Gesamt)
[1] "integer"

> print(mydata)
        Gruppen Abweichung BW_Gesamt
1      (0,5000]          5   7088028
2  (5000,10000]          2   7292184
3 (10000,15000]          0         0
4 (15000,20000]          1   5389585

变异Abweichung和变异BW_Gesamt有区别,因为我发现Abweichung将被更改为整数,而BW_Gesamt仍然是数字。

我不知道这种方法有多高效,我在这里找到了它: LINK 感谢AntoniosK

也许有人知道如何优化它。在我看来,它具有改变组的结果的优点。所以我可以显示BW_Gesamt的总和,同时显示Abweichung的出现次数。

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