从文件中读取省略上三角部分的对称矩阵 [英] Reading a symmetric matrix from file that omits upper triangular part

问题描述

使用R，从省略上三角部分的文件中读取对称矩阵的最佳方法是什么.例如，

Using R, what is the best way to read a symmetric matrix from a file that omits the upper triangular part. For example,

1.000
.505  1.000
.569  .422  1.000
.602  .467  .926  1.000
.621  .482  .877  .874  1.000
.603  .450  .878  .894  .937  1.000

我尝试了read.table，但是没有成功.

I have tried read.table, but haven't been successful.

推荐答案

这是一个read.table和无环且* apply-less解决方案:

Here's a read.table and loopless and *apply-less solution:

txt <- "1.000
.505  1.000
.569  .422  1.000
.602  .467  .926  1.000
.621  .482  .877  .874  1.000
.603  .450  .878  .894  .937  1.000"
 # Could use clipboard or read this from a file as well.
mat <- data.matrix( read.table(text=txt, fill=TRUE, col.names=paste("V", 1:6))  )
mat[upper.tri(mat)] <- t(mat)[upper.tri(mat)]
> mat
        V1    V2    V3    V4    V5    V6 
[1,] 1.000 0.505 0.569 0.602 0.621 0.603
[2,] 0.505 1.000 0.422 0.467 0.482 0.450
[3,] 0.569 0.422 1.000 0.926 0.877 0.878
[4,] 0.602 0.467 0.926 1.000 0.874 0.894
[5,] 0.621 0.482 0.877 0.874 1.000 0.937
[6,] 0.603 0.450 0.878 0.894 0.937 1.000

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