standard inverse cell frequency
idf(expr, features = NULL, thres = 0)
Arguments
- expr
a matrix, features in row and cells in column
- features
vector, feature names or indexes to compute
- thres
numeric, cell only counts when expr > threshold, default 0
Value
a vector of inverse cell frequency score for each feature
Details
$$\mathbf{IDF_i} = log(1+\frac{n}{n_i+1})$$
where \(n\) is the total number of cells, \(n_i\) is the number of cells
containing feature i.
Examples
data <- matrix(rpois(100, 2), 10, dimnames = list(1:10))
smartid:::idf(data)
#> 1 2 3 4 5 6 7 8
#> 0.7472144 0.6466272 0.8109302 0.6466272 0.7472144 0.6931472 0.6931472 0.8873032
#> 9 10
#> 0.6466272 0.7472144