R中的分组移动平均值 [英] Grouped moving average in r
问题描述
我正在尝试计算特定字段在r中的移动平均值，但我需要将此移动平均值按两个或多个其他字段进行分组.这个新平均数的目的是用于预测分析，因此我也需要追踪它. 理想情况下，任何没有足够平均值进行平均的变量(例如学生J)都将给出NA或原始得分值.
I'm trying to calculate a moving average in r over a particular field BUT I need this moving average to be grouped by two or more other fields. The purpose of this new average is for predictive analysis so I need it to be trailing as well. Any variables that do not have enough values to be averaged (such as student J) would ideally give either NA or its original Score value.
我一直在尝试rollapply和data.table，但没有运气！
I've been trying rollapply and data.table and am having no luck!
我提供了数据表和两个移动平均值(k = 2的AVG2和k = 3的AVG3)，以准确显示我的要求.移动平均值在分数"上，要分组的变量是学校，学生和区域.请帮忙！
I've provided the table of data and two moving averages (AVG2 with k=2 and AVG3 with k=3) to show exactly what I'm after. The moving average is on Score and the variables to group over are school, Student and area. Please help!
no school Student area Score **AVG2** **AVG3**
1 I S A 5 NA NA
2 B S A 2 NA NA
3 B S A 7 NA NA
4 B O A 3 NA NA
5 B O B 9 NA NA
6 I O A 6 NA NA
7 I O B 3 NA NA
8 I S A 7 NA NA
9 I O A 1 NA NA
10 B S A 7 4.5 NA
11 I S A 3 NA NA
12 I O A 8 3.5 NA
13 B S A 3 7 5.33
14 I O A 4 4.5 5
15 B O A 1 NA NA
16 I S A 9 5 5
17 B S A 4 5 5.67
18 B O A 6 2 NA
19 I S A 3 6 6.33
20 I O B 8 NA NA
21 B S A 3 3.5 4.67
22 I O A 4 6 4.33
23 B O A 1 3.5 3.33
24 I S A 9 6 5
25 B S A 4 3.5 3.33
26 B O A 6 3.5 2.67
27 I J A 6 NA NA
下面是在r中重新创建初始表的代码:
here is the code to recreate the initial table in r:
school <- c('I','B','B','B','B','I','I','I','I','B','I','I','B','I','B','I','B','B','I','I','B','I','B','I','B','B','I')
Student <- c('S','S','S','O','O','O','O','S','O','S','S','O','S','O','O','S','S','O','S','O','S','O','O','S','S','O','J')
area <- c('A','A','A','A','B','A','B','A','A','A','A','A','A','A','A','A','A','A','A','B','A','A','A','A','A','A','A')
Score <- c(5,2,7,3,9,6,3,7,1,7,3,8,3,4,1,9,4,6,3,8,3,4,1,9,4,6,6)
data.frame(school, Student, area, Score)
推荐答案
这是rollapply解决方案.请注意，您似乎希望获得同一组中前两或三行的平均值，即排除当前行中的数据.
Here is a rollapply solution. Note that it appears that you want the average of the prior two or three rows in the same group, i.e. excluding the data on the current row.
library(zoo)
roll <- function(x, n) {
if (length(x) <= n) NA
else rollapply(x, list(-seq(n)), mean, fill = NA)
}
transform(DF, AVG2 = ave(Score, school, Student, FUN = function(x) roll(x, 2)),
AVG3 = ave(Score, school, Student, FUN = function(x) roll(x, 3)))
给予:
school Student Score AVG2 AVG3
1 I S 5 NA NA
2 B S 2 NA NA
3 B S 7 NA NA
4 B O 3 NA NA
5 B O 9 NA NA
6 I O 6 NA NA
7 I O 3 NA NA
8 I S 7 NA NA
9 I O 1 4.5 NA
10 B S 7 4.5 NA
11 I S 3 6.0 NA
12 I O 8 2.0 3.333333
13 B S 3 7.0 5.333333
14 I O 4 4.5 4.000000
15 B O 1 6.0 NA
16 I S 9 5.0 5.000000
17 B S 4 5.0 5.666667
18 B O 6 5.0 4.333333
19 I S 3 6.0 6.333333
20 I O 8 6.0 4.333333
21 B S 3 3.5 4.666667
22 I O 4 6.0 6.666667
23 B O 1 3.5 5.333333
24 I S 9 6.0 5.000000
25 B S 4 3.5 3.333333
26 B O 6 3.5 2.666667
27 I J 6 NA NA
更新:固定辊.
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