rowProds: Calculates the product for each row (column) in a matrix
In matrixStats: Functions that Apply to Rows and Columns of Matrices (and to Vectors)

product

R Documentation

Calculates the product for each row (column) in a matrix

Description

Calculates the product for each row (column) in a matrix.

Usage

product(x, idxs = NULL, na.rm = FALSE, ...)

rowProds(x, rows = NULL, cols = NULL, na.rm = FALSE,
  method = c("direct", "expSumLog"), ..., useNames = TRUE)

colProds(x, rows = NULL, cols = NULL, na.rm = FALSE,
  method = c("direct", "expSumLog"), ..., useNames = TRUE)

Arguments

`x`	An NxK `matrix` or, if `dim.` is specified, an N * K `vector`.
`idxs`	A `vector` indicating subset of elements to operate over. If `NULL`, no subsetting is done.
`na.rm`	If `TRUE`, missing values are excluded.
`...`	Not used.
`rows`	A `vector` indicating subset of rows to operate over. If `NULL`, no subsetting is done.
`cols`	A `vector` indicating subset of columns to operate over. If `NULL`, no subsetting is done.
`method`	A `character` string specifying how each product is calculated.
`useNames`	If `TRUE` (default), names attributes of the result are set, otherwise not.

Details

If method = "expSumLog", then then product() function is used, which calculates the product via the logarithmic transform (treating negative values specially). This improves the precision and lowers the risk for numeric overflow. If method = "direct", the direct product is calculated via the prod() function.

Value

Returns a numeric vector of length N (K).

Missing values

Note, if method = "expSumLog", na.rm = FALSE, and x contains missing values (NA or NaN), then the calculated value is also missing value. Note that it depends on platform whether NaN or NA is returned when an NaN exists, cf. is.nan().