为什么我只能从R中的cor（）函数中获取1和-1？

我正在尝试执行与cor（）函数的Pearson相关性，但输出结果只给出了1和-1，而不是系数本身。所以当我用corrplot（）绘制矩阵时，我只能看到那些1和-1值。我该如何解决？我的数据集可以发现here，看看我的脚本楼下：为什么我只能从R中的cor（）函数中获取1和-1？

##Must load the libraries we will need! IF you have not installed the packages, do that before you start. 
library("corrplot") 
##Load in your datasets 
D1=BPT5test 
##if you don't have a Y (i.e, you want the same thing to be in both axis), leave this blank 
D2= 
##Run the spearman correlation. If you want to do a Pearson, change "spearman to "pearson" 
##If you have 0s in your dataset, set use = "complete.obs", if you have no 0s, set use = "everything" 
CorTest=cor(D1, use = "everything", method = "pearson") 
##Let's get to plotting! 
##Lots of changing you can do! 
#Method can be "circle" "square" "pie" "color" 
#ColorRampPalette can be changed, "blue" being the negative, "White" being '0', and "red" being the positive 
#Change the title to whatever you want it to be 
#tl.col is the color of your labels, this can be set to anything.. default is red 
CorGraph=corrplot(CorTest, method = "circle", col = colorRampPalette(c("blue","white","red"))(200), title = "Pearson's Correlation of High-Fat Sugar at 8 weeks", tl.cex = .5, tl.col = "Black",diag = TRUE, cl.ratio = 0.2)

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2017-07-25 Haley

您的数据集包含每个变量只有2个观察值。任何两个由只有两个观察值组成的变量之间的相关性始终为-1或1.要亲眼看看，请尝试运行replicate(1e2, cor(rnorm(2), rnorm(2)))，其中计算两个观察值组成的两个变量之间的100个相关性。结果始终是-1或1.

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2017-07-25 20:27:31 Vandenman

谢谢你，显然我对统计学的知识缺乏了我最好的。 – Haley

这是因为你只有两个柱意见。

test <- data.frame(a=c(1,2),b=c(2,3),c=c(4,-2)) 
cor(test, use = "everything", method = "pearson") 
    a b c 
a 1 1 -1 
b 1 1 -1 
c -1 -1 1

您不能指望只有两个值的不同输出，请检查Pearson correlation formula。

由于三个或更多，你将有更多的变化：

test <- data.frame(a=c(1,2,3),b=c(2,3,5),c=c(4,-2,-10)) 
cor(test, use = "everything", method = "pearson") 
      a   b   c 
a 1.0000000 0.9819805 -0.9966159 
b 0.9819805 1.0000000 -0.9941916 
c -0.9966159 -0.9941916 1.0000000

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2017-07-25 20:27:25

为什么我只能从R中的cor（）函数中获取1和-1？

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