topRank() can quickly identify the top `n` rows for each column of a matrix. For example, this can be useful for identifying the top `n` features per cell.
topRank(matrix, n = 25, margin = 2, threshold = 0, decreasing = TRUE)Numeric matrix.
Integer. Maximum number of items above `threshold` returned for each ranked row or column.
Integer. Dimension of `matrix` to rank, with 1 for rows, 2 for columns. Default 2.
Numeric. Only return ranked rows or columns in the matrix that are above this threshold. If NULL, then no threshold will be applied. Default 0.
Logical. Specifies if the rank should be decreasing. Default TRUE.
List. The `index` variable provides the top `n` row (feature) indices contributing the most to each column (cell). The `names` variable provides the rownames corresponding to these indexes.
data(sampleCells)
topRanksPerCell <- topRank(sampleCells, n = 5)
topFeatureNamesForCell <- topRanksPerCell$names[1]