将R中的数据分组以执行功能 [英] Grouping data in R to perform a function
问题描述
以下是我的数据示例:
id score
1 82 0.50000
2 82 0.39286
3 82 0.56250
4 328 0.50000
5 328 0.67647
6 328 0.93750
7 328 0.91667
我想为每个ID制作一列移动平均分数.
I want to make a column of moving average's of scores for each id.
所以我需要通过id对数据进行分组,然后将MA函数应用于该分组数据,然后将输出作为另一列"MA_score"
So I need to somehow group the data by id then apply a MA function to that grouped data and then have the output as another column "MA_score"
我希望我的输出看起来像这样:
I would like my output to look like this:
id score MA_score
1 82 0.50000 NULL
2 82 0.39286 0.xxxx
3 82 0.56250 NULL
4 328 0.50000 NULL
5 328 0.67647 0.yyyy
6 328 0.93750 0.qqqq
7 328 0.91667 NULL
推荐答案
您可以使用zoo包中的split和rollapply作为解决此问题的多种方法之一.请注意,在下面的示例中,我将rollapply函数的宽度设置为1,因此它仅返回每个值.对于大于1的宽度,它将采用该数量的值的平均值.
You could use split and rollapply from the zoo package as one of many ways to approach this. Note that in the example below I set the width of the rollapply function to 1 so it just returns each value. For widths greater than one it will take the mean of that number of values.
require(zoo)
sapply( split( df , df$id) , function(x) rollapply( x , width = 1 , align = 'left' , mean) )
#Note that by setting width = 1 we just return the value
$`82`
id score
[1,] 82 0.50000
[2,] 82 0.39286
[3,] 82 0.56250
$`328`
id score
[1,] 328 0.50000
[2,] 328 0.67647
[3,] 328 0.93750
[4,] 328 0.91667
如果我们设置width = 3
,您将得到:
If we were to set width = 3
you would get:
$`82`
id score
[1,] 82 0.48512
$`328`
id score
[1,] 328 0.7046567
[2,] 328 0.8435467
或者您可以在base
R中使用聚合:
Or you could use aggregate in base
R:
aggregate( score ~ id , data = df , function(x) rollapply( x , width = 1 , align = 'left' , mean) )
id score
1 82 0.50000, 0.39286, 0.56250
2 328 0.50000, 0.67647, 0.93750, 0.91667
有很多方法可以做到这一点.不过,我会精确定义您的移动平均函数,因为有很多方法可以计算它(例如,请查看TTR:::SMA
)
There are quite a few ways to do this. I would precisely define your moving average function though, because there are many ways to calculate it (check out for example TTR:::SMA
)
或更简单的使用ave
:
within(df, { MA_score <- ave(score, id, FUN=function(x)
rollmean(x, k=3, na.pad = TRUE))})
这篇关于将R中的数据分组以执行功能的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!