Transform expression matrix to long data frame

This function takes a matrix (columns are samples, rows are genes), and converts it into a 'long' data frame suitable for plotting It also handles sorting the data by chromosomal coordinate.

expression_matrix_to_long_df(expression.mat, genes.bed)

Arguments

expression.mat	A matrix of expression values.
genes.bed	A bed-like file containing gene coordinates.

Value

expression.long.df