dim（X）的R长度必须为正

Question

I want to see how many positive and negative I have in a matrix I simply use the following command to get the negative values but I get error

apply(m[,2], 2, function(x) length(x[x<0]))

My matrix look like following and named m

    row.names   logFC        AveExpr       t         P.Value    adj.P.Val       B
1   AFFX    0.254330303 -0.0273913479   2.790941    0.005346628 0.9936675   -2.351052
2   AFFX-   0.144249680 -0.0081323315   2.744752    0.006154509 0.9936675   -2.470447
3   AFFX-T  0.129062121 -0.0072936248   2.730567    0.006423832 0.9936675   -2.506720
4   AFFy    0.105893838 -0.0084886157   2.672831    0.007632963 0.9936675   -2.652445
5   AFfm    0.146253131 -0.0123657559   2.617852    0.008970330 0.9936675   -2.788357
6   20uy    1.033582071 0.9319210383    2.476302    0.013425076 0.9936675   -3.125444
7   2196    0.099556431 -0.0061285974   2.451229    0.014392052 0.9936675   -3.183222



**Error in apply(m[, 2], 2, function(x) length(x[x < 0])) : 
  dim(X) must have a positive length**

Answer 1

You can just type:

sum(m<0)

which gives you the number of negative values of the whole matrix. If you want it for each row or column, then

colSums(m<0)

and

rowSums(m<0)

will give you the answer