Export MEX Expression Matrix

For export in MEX format, a number of options can be specified:

The export outputs barcodes, features, and expressions to barcodes.tsv, features.tsv, and matrix.mtx, respectively. If the matrix is an Expression Matrix with spliced and unspliced counts (Image expr_matrix_spliced_unspliced_16_n_p), two additional files are produced containing spliced (spliced.mtx) and unspliced (unspliced.mtx) counts.