gene expression data

Determine genes that are expressed in a dataset. Expressed genes are those that have expression in a range (min.expression, max.expression)

1 2	E3GetExpressedGenes(dlist, id.col = "Gene", min.expression = 1, max.expression = Inf, min.count = 1)

`dlist`	- a list of dataframes, one of which must be $expression. Data frames must have one identifier column and the remaining columns will be treated as samples.
`id.col`	- character string. Name of column that contain gene identifier
`min.expression`	- numeric. Minimal expression level
`max.expression`	- numeric. Maximal expression level
`min.count`	- integer. Number of samples that must lie in range [min.expression, max.expression]. Use this to require a gene to be expressed in several samples in a cohort.