我有这个数据框，（df1）：
Month index
1 2015-09-01 1.21418847
2 2015-08-01 -4.37919039
3 2015-07-01 -1.16004624
4 2015-06-01 -1.09754890
5 2015-05-01 -4.37919039
6 2015-04-01 -4.37919039
7 2015-03-01 4.37919039
8 2015-02-01 4.37919039
9 2015-01-01 -0.11285150
10 2014-12-01 0.45712044
11 2014-11-01 0.97597018
12 2014-10-01 0.87560496
13 2014-09-01 0.66278156
14 2014-08-01 4.37919039
15 2014-07-01 1.15440685
16 2014-06-01 1.38021497
17 2014-05-01 1.67663242
18 2014-04-01 2.08358406
19 2014-03-01 2.50222843
20 2014-02-01 2.71665822
21 2014-01-01 3.13692051
22 2013-12-01 2.91702023
23 2013-11-01 3.02603774
24 2013-10-01 2.55812363
25 2013-09-01 3.12586325
26 2013-08-01 3.26063617
27 2013-07-01 2.91702023
28 2013-06-01 3.15504505
29 2013-05-01 2.53958494
30 2013-04-01 2.61528861
31 2013-03-01 2.84742861
32 2013-02-01 2.82097624
33 2013-01-01 2.53196473
34 2012-12-01 2.35786991
35 2012-11-01 2.40611260
36 2012-10-01 2.42408844
37 2012-09-01 2.91702023
38 2012-08-01 2.33372249
39 2012-07-01 2.00140636
40 2012-06-01 2.24721387
41 2012-05-01 1.89189602
42 2012-04-01 1.98807663
43 2012-03-01 1.89563925
44 2012-02-01 1.19541625
45 2012-01-01 2.91702023
46 2011-12-01 0.29072412
47 2011-11-01 -2.91702023
48 2011-10-01 -2.91702023
49 2011-09-01 -0.36402331
50 2011-08-01 -0.55409805
51 2011-07-01 -0.05902839
52 2011-06-01 -0.03946940
53 2011-05-01 0.30898661
54 2011-04-01 2.91702023
55 2011-03-01 0.80556310
56 2011-02-01 1.07001901
57 2011-01-01 2.91702023
58 2010-12-01 1.34682208
59 2010-11-01 1.30446466
60 2010-10-01 0.97753435
61 2010-09-01 0.90434619
62 2010-08-01 0.80415571
63 2010-07-01 1.41129808
64 2010-06-01 2.03576435
65 2010-05-01 2.85757135
66 2010-04-01 2.91702023
67 2010-03-01 3.96563441
68 2010-02-01 4.37919039
69 2010-01-01 4.57358010
70 2009-12-01 4.63589893
71 2009-11-01 4.40042885
72 2009-10-01 4.21359930
73 2009-09-01 4.10739350
74 2009-08-01 2.91702023
75 2009-07-01 3.85460338
76 2009-06-01 3.07796824
77 2009-05-01 2.91702023
78 2009-04-01 1.90359672
79 2009-03-01 0.68355248
80 2009-02-01 0.36218125
81 2009-01-01 -0.50814101
82 2008-12-01 0.49310633
83 2008-11-01 2.98877210
84 2008-10-01 2.28716199
85 2008-09-01 0.61433048
86 2008-08-01 0.51258623
87 2008-07-01 1.74079440
88 2008-06-01 2.91702023
89 2008-05-01 1.60899848
90 2008-04-01 2.01574569
91 2008-03-01 1.81341196
92 2008-02-01 1.48482933
93 2008-01-01 1.89122725
94 2007-12-01 1.84400308
95 2007-11-01 1.23545695
96 2007-10-01 0.44341718
97 2007-09-01 0.55630846
98 2007-08-01 0.42806839
99 2007-07-01 -0.75234218
100 2007-06-01 -1.44397151
101 2007-05-01 -2.10673018
102 2007-04-01 -1.40817350
103 2007-03-01 -0.73608848
104 2007-02-01 -0.69200513
105 2007-01-01 -0.51056142
106 2006-12-01 -0.40504212
107 2006-11-01 -0.04161989
108 2006-10-01 -0.10478629
109 2006-09-01 0.07423530
110 2006-08-01 0.13076121
111 2006-07-01 2.91702023
112 2006-06-01 1.02865488
113 2006-05-01 -0.08979180
114 2006-04-01 -1.52792341
115 2006-03-01 -2.52839603
116 2006-02-01 -3.39026284
117 2006-01-01 -3.04045769
我想计算每年的季度平均值。这将导致data.frame有39行。
我执行此代码来实现季度平均值：
final<-df1[, mean(index), by = quarterly(Month)]
错误mssg是：
Error in `[.data.frame`(df1, , mean(index), :
unused argument (by = month(Month))
信息：
class(df1$index)
"numeric"
class(df1$Month)
"factor"
我做错了什么？
由于
答案 0 :(得分：3)
您似乎正在尝试在数据框上使用 data.table 语法。所以先做
library(data.table)
setDT(df1)
加载 data.table 包并将df1设置为数据表。然后就可以了
final <- df1[, mean(index), keyby = .(year(Month), quarter(Month))]
str(final)
# Classes ‘data.table’ and 'data.frame': 39 obs. of 3 variables:
# $ year : int 2006 2006 2006 2006 2007 2007 2007 2007 2008 2008 ...
# $ quarter: int 1 2 3 4 1 2 3 4 1 2 ...
# $ V1 : num -2.986 -0.196 1.041 -0.184 -0.646 ...
# - attr(*, "sorted")= chr "year" "quarter"
# - attr(*, ".internal.selfref")=<externalptr>
这表明我们在结果中有39行，如您所愿。一些注意事项：该函数名为quarter()而非quarterly()，您需要M中的资金Month，并且需要按年份和季度进行分组。