!!!as.data.frame()　行列データをデータフレームとして扱えるようにする
{{pre
> matrix(rnorm(20),10)
            [,1]        [,2]
 [1,]  1.2642709  0.40845275
 [2,] -0.2550768  2.84615911
 [3,]  1.1184453  1.82122937
 [4,]  0.7177743  0.46157298
 [5,] -0.7636240  0.18649371
 [6,] -1.6880682  1.09607064
 [7,]  1.0707097  1.27204158
 [8,]  2.7192425  0.09982795
 [9,]  1.5079816 -1.22006999
[10,]  0.1532460 -0.26429986
> as.data.frame(matrix(rnorm(20),10))
            V1         V2
1  -2.95717100  1.9471920
2  -0.43985089 -0.6219538
3  -0.61734663  0.1250249
4   0.01641657  2.9194738
5  -1.90443165  0.4637816
6  -1.67740306  1.6186700
7   0.94506705  1.0557857
8  -0.37899424 -0.8025818
9   0.58899355  0.5481681
10  0.81805886 -1.5261921
}}