我有一个稀疏矩阵，当我用R打开它时，所有应该是0的元素都像'我怎么能把这个点化为0呢?

I had a sparse matrix, when I open it in R, all elements which should be 0 are dots like ' . ', how can I convert it this dot to number 0? That is converting it to numeric matrix that can be used in following calculation.I had a sparse matrix, when I open it in R, all