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R中矩阵的滚动标准偏差

转载 作者:行者123 更新时间:2023-12-03 15:18:08 25 4
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Bellow 是股票日 yield 矩阵示例 ( ret_matriz )

      IBOV        PETR4        VALE5        ITUB4        BBDC4        PETR3    
[1,] -0.040630825 -0.027795652 -0.052643733 -0.053488685 -0.048455772 -0.061668282
[2,] -0.030463489 -0.031010237 -0.047439725 -0.040229625 -0.030552275 -0.010409016
[3,] -0.022668170 -0.027012078 -0.022668170 -0.050372843 -0.080732363 0.005218051
[4,] -0.057468428 -0.074922051 -0.068414670 -0.044130126 -0.069032911 -0.057468428
[5,] 0.011897277 -0.004705891 0.035489885 -0.005934736 -0.006024115 -0.055017693
[6,] 0.020190656 0.038339130 0.009715552 0.014771317 0.023881732 0.011714308
[7,] -0.007047191 0.004529286 0.004135085 0.017442303 -0.005917177 -0.007047191
[8,] -0.022650593 -0.029481336 -0.019445057 -0.017442303 -0.011940440 -0.046076458
[9,] 0.033137223 0.035274722 0.038519205 0.060452104 0.017857617 0.046076458

例如,考虑一个 5 天的移动窗口,因此我想要一个如下所述的新矩阵:
     IBOV        PETR4    ...       
[1,] 0 0 ...
[2,] 0 0 ...
[3,] 0 0 ...
[4,] 0 0 ...
[5,] sd[1:5,1] sd[1:5,2] ...
[6,] sd[2:6,1] sd[2:6,2] ...
[7,] sd[3:7,1] sd[3:7,2] ...
[8,] sd[4:8,1] sd[4:8,2] ...
[9,] sd[5:9,1] sd[5:9,2] ...

使用 zoo 包我能够达到结果,但速度有点慢,关于如何提高速度以达到相同结果的任何想法?

动物园代码如下:
require(zoo)

apply(ret_matriz, 2, function(x) rollapply(x, width = 5, FUN = sd, fill = 0, align = 'r'))

最佳答案

1) apply部分可以消除。我们也使用 rollapplyr为简洁起见:

rollapplyr(ret_matriz, 5, sd, fill = 0)

2) 还有 rollmeanrollapply 快所以我们可以使用公式 sd = sqrt(n/(n-1) * (mean(x^2) - mean(x)^2)) 从中构造它:
sqrt((5/4) * (rollmeanr(ret_matriz^2, 5, fill = 0) - 
rollmeanr(ret_matriz, 5, fill = 0)^2))

关于R中矩阵的滚动标准偏差,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/24066085/

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