循环查找两个不同数据格式中相同变量(列)之间的相关性。

Question

我有两个数据文件: CNA和mrna_zscores。我试图使用这个for循环来查找两个数据文件中相同变量(列)之间的关联，但是它返回一个空向量(NULL).出什么问题了？

for(i in 1:50){
   cor_CNA_mRNA_kendall <- cor(CNA[, i], mrna_zscores[, i], method = "kendall")
}

我得到了我想要的结果，但是有很多代码，不太有用.

cor_CNA_mRNA_kendall <- c(cor(CNA[, 1], mrna_zscores[, 1], method = "kendall"), cor(CNA[, 2], mrna_zscores[, 2], method = "kendall"), cor(CNA[, 3], mrna_zscores[, 3], method = "kendall"), cor(CNA[, 4], mrna_zscores[, 4], method = "kendall"), cor(CNA[, 5], mrna_zscores[, 5], method = "kendall"), cor(CNA[, 6], mrna_zscores[, 6], method = "kendall"), cor(CNA[, 7], mrna_zscores[, 7], method = "kendall"), cor(CNA[, 8], mrna_zscores[, 8], method = "kendall"), cor(CNA[, 9], mrna_zscores[, 9], method = "kendall"), cor(CNA[, 10], mrna_zscores[, 10], method = "kendall"), cor(CNA[, 11], mrna_zscores[, 11], method = "kendall"), cor(CNA[, 12], mrna_zscores[, 12], method = "kendall"), cor(CNA[, 13], mrna_zscores[, 13], method = "kendall"), cor(CNA[, 14], mrna_zscores[, 14], method = "kendall"), cor(CNA[, 15], mrna_zscores[, 15], method = "kendall"), cor(CNA[, 16], mrna_zscores[, 16], method = "kendall"), cor(CNA[, 17], mrna_zscores[, 17], method = "kendall"), cor(CNA[, 18], mrna_zscores[, 18], method = "kendall"), cor(CNA[, 19], mrna_zscores[, 19], method = "kendall"), cor(CNA[, 20], mrna_zscores[, 20], method = "kendall"), cor(CNA[, 21], mrna_zscores[, 21], method = "kendall"), cor(CNA[, 22], mrna_zscores[, 22], method = "kendall"), cor(CNA[, 23], mrna_zscores[, 23], method = "kendall"), cor(CNA[, 24], mrna_zscores[, 24], method = "kendall"), cor(CNA[, 25], mrna_zscores[, 25], method = "kendall"), cor(CNA[, 26], mrna_zscores[, 26], method = "kendall"), cor(CNA[, 27], mrna_zscores[, 27], method = "kendall"), cor(CNA[, 28], mrna_zscores[, 28], method = "kendall"), cor(CNA[, 29], mrna_zscores[, 29], method = "kendall"), cor(CNA[, 30], mrna_zscores[, 30], method = "kendall"), cor(CNA[, 31], mrna_zscores[, 31], method = "kendall"), cor(CNA[, 32], mrna_zscores[, 32], method = "kendall"), cor(CNA[, 33], mrna_zscores[, 33], method = "kendall"), cor(CNA[, 34], mrna_zscores[, 34], method = "kendall"), cor(CNA[, 35], mrna_zscores[, 35], method = "kendall"), cor(CNA[, 36], mrna_zscores[, 36], method = "kendall"), cor(CNA[, 37], mrna_zscores[, 37], method = "kendall"), cor(CNA[, 38], mrna_zscores[, 38], method = "kendall"), cor(CNA[, 39], mrna_zscores[, 39], method = "kendall"), cor(CNA[, 40], mrna_zscores[, 40], method = "kendall"), cor(CNA[, 41], mrna_zscores[, 41], method = "kendall"), cor(CNA[, 42], mrna_zscores[, 42], method = "kendall"), cor(CNA[, 43], mrna_zscores[, 43], method = "kendall"), cor(CNA[, 44], mrna_zscores[, 44], method = "kendall"), cor(CNA[, 45], mrna_zscores[, 45], method = "kendall"), cor(CNA[, 46], mrna_zscores[, 46], method = "kendall"), cor(CNA[, 47], mrna_zscores[, 47], method = "kendall"), cor(CNA[, 48], mrna_zscores[, 48], method = "kendall"), cor(CNA[, 49], mrna_zscores[, 49], method = "kendall"), cor(CNA[, 50], mrna_zscores[, 50], method = "kendall"))

为什么在dataframe名称之后不使用没有括号的cor函数？好吧，它还给我这样的关联: V1xV1，V1xV2，V1xV3.V2xV1，V2xV2，V2xV3.V3xV1，V3xv2，V3xV3.

我只想要一个带有V1xV1，V2xV2，V3xV3的向量。

Answer 1

如前所述，您需要创建一个变量来填充。

correlations<-data.frame()
for(i in 1:50){
   cor_CNA_mRNA_kendall <- cor(CNA[, i], mrna_zscores[, i], method = "kendall")
   correlations<-rbind(correlations,cor_CNA_mRNA_kendall)
}

Answer 2

与R中通常的情况一样，最好的方法是不使用for循环。本质上，你所追求的是方差协方差矩阵的对角线。因此，您应该集中精力提取对角线。

使用R基

d1 <- matrix(sample(100), 10, 10)
d2 <- matrix(sample(100), 10, 10)

cor(d1, d2, method = "kendall")[as.logical(diag(nrow(d1)))]

使用OpenMx软件包

library(OpenMx)

diag2vec(cor(d1, d2, method = "kendall"))