使用數據表分組後包括列

Question

我的目標是通過zip計算組％列。我通過zip創建了％列，但不斷失去我的組（'cgrp'）變量。我如何在最終結果中保留這一點？

我的數據表腳本是給我下面的結果：

 zip  V1 
1: 12007 19.35484 
2: 12007 48.38710 
3: 12007 32.25806 
4: 12008 40.00000 
5: 12008 41.66667 
6: 12008 18.33333 

，但我也想列cgrp包括在內。一直在努力的.SD和SDcols不同的組合，但它不能得到work.This是我想要的東西：

 zip  V1 cgrp 
1: 12007 19.35484 3 
2: 12007 48.38710 4 
3: 12007 32.25806 1 
4: 12008 40.00000 1 
5: 12008 41.66667 4 
6: 12008 18.33333 3 

腳本：

zip.grp <- ninefive[, .(zgrp = .N), by = .(cgrp,zip) 
        ][, 100 *(zgrp/sum(zgrp)), by = zip] 

樣本ninefive數據：

zip  lower avg upper  SSN RISK idk diff avgDiff cgrp 
1: 12007 -170.3723 592 1354.372 127 676 1 84 137.2903 3 
2: 12007 -170.3723 592 1354.372 064 828 1 236 137.2903 4 
3: 12007 -170.3723 592 1354.372 080 627 1 35 137.2903 1 
4: 12007 -170.3723 592 1354.372 057 770 1 178 137.2903 4 
5: 12007 -170.3723 592 1354.372 014 770 1 178 137.2903 4 
6: 12007 -170.3723 592 1354.372 084 893 1 301 137.2903 4 
7: 12007 -170.3723 592 1354.372 105 757 1 165 137.2903 4 
8: 12007 -170.3723 592 1354.372 093 494 1 98 137.2903 1 
9: 12007 -170.3723 592 1354.372 080 744 1 152 137.2903 4 
10: 12007 -170.3723 592 1354.372 102 494 1 98 137.2903 1 
11: 12007 -170.3723 592 1354.372 062 748 1 156 137.2903 4 
12: 12007 -170.3723 592 1354.372 729 711 1 119 137.2903 3 
13: 12007 -170.3723 592 1354.372 059 677 1 85 137.2903 3 
14: 12007 -170.3723 592 1354.372 090 718 1 126 137.2903 3 
15: 12007 -170.3723 592 1354.372 053 636 1 44 137.2903 1 
16: 12007 -170.3723 592 1354.372 081 855 1 263 137.2903 4 
17: 12007 -170.3723 592 1354.372 073 811 1 219 137.2903 4 
18: 12007 -170.3723 592 1354.372 092 614 1 22 137.2903 1 
19: 12007 -170.3723 592 1354.372 081 789 1 197 137.2903 4 
20: 12007 -170.3723 592 1354.372 105 831 1 239 137.2903 4 
21: 12007 -170.3723 592 1354.372 108 809 1 217 137.2903 4 
22: 12007 -170.3723 592 1354.372 093 649 1 57 137.2903 1 
23: 12007 -170.3723 592 1354.372 128 685 1 93 137.2903 3 
24: 12007 -170.3723 592 1354.372 093 574 1 18 137.2903 1 
25: 12007 -170.3723 592 1354.372 119 640 1 48 137.2903 1 
26: 12007 -170.3723 592 1354.372 163 813 1 221 137.2903 4 
27: 12007 -170.3723 592 1354.372 062 678 1 86 137.2903 3 
28: 12007 -170.3723 592 1354.372 102 652 1 60 137.2903 1 
29: 12007 -170.3723 592 1354.372 379 532 1 60 137.2903 1 
30: 12007 -170.3723 592 1354.372 107 803 1 211 137.2903 4 
31: 12007 -170.3723 592 1354.372 060 782 1 190 137.2903 4 
32: 12008 -262.0840 729 1720.084 110 547 1 182 104.8667 1 
33: 12008 -262.0840 729 1720.084 023 821 1 92 104.8667 4 
34: 12008 -262.0840 729 1720.084 072 649 1 80 104.8667 1 
35: 12008 -262.0840 729 1720.084 119 602 1 127 104.8667 1 
36: 12008 -262.0840 729 1720.084 076 553 1 176 104.8667 1 
37: 12008 -262.0840 729 1720.084 083 606 1 123 104.8667 1 
38: 12008 -262.0840 729 1720.084 124 645 1 84 104.8667 1 
39: 12008 -262.0840 729 1720.084 086 700 1 29 104.8667 3 
40: 12008 -262.0840 729 1720.084 063 579 1 150 104.8667 1 
41: 12008 -262.0840 729 1720.084 086 746 1 17 104.8667 4 
42: 12008 -262.0840 729 1720.084 075 732 1 3 104.8667 4 
43: 12008 -262.0840 729 1720.084 082 656 1 73 104.8667 1 
44: 12008 -262.0840 729 1720.084 057 515 1 214 104.8667 1 
45: 12008 -262.0840 729 1720.084 068 806 1 77 104.8667 4 
46: 12008 -262.0840 729 1720.084 103 797 1 68 104.8667 4 
47: 12008 -262.0840 729 1720.084 110 578 1 151 104.8667 1 
48: 12008 -262.0840 729 1720.084 102 709 1 20 104.8667 3 
49: 12008 -262.0840 729 1720.084 565 567 1 162 104.8667 1 
50: 12008 -262.0840 729 1720.084 037 886 1 157 104.8667 4 

Answer 1

您可以使用:=創建一個新列

ninefive[, .(zgrp=.N), by= .(cgrp, zip)][, V1:=100*(zgrp/sum(zgrp)), 
       by=zip][, zgrp:=NULL] 
# cgrp zip  V1 
#1: 3 12007 19.35484 
#2: 4 12007 48.38710 
#3: 1 12007 32.25806 
#4: 1 12008 57.89474 
#5: 4 12008 31.57895 
#6: 3 12008 10.52632 

或者作爲@Frank評論，你可以包括list

ninefive[, .(zgrp=.N), by= .(cgrp, zip)][, list(cgrp,V1=100* 
       (zgrp/sum(zgrp))), by=zip] 
#  zip cgrp  V1 
#1: 12007 3 19.35484 
#2: 12007 4 48.38710 
#3: 12007 1 32.25806 
#4: 12008 1 57.89474 
#5: 12008 4 31.57895 
#6: 12008 3 10.52632