fprod is a generic function that computes the (column-wise) product of all values in x, (optionally) grouped by g and/or weighted by w. The TRA argument can further be used to transform x using its (grouped, weighted) product.
fprod(x, ...)# S3 method for default
fprod(x, g = NULL, w = NULL, TRA = NULL, na.rm = .op[["na.rm"]],
use.g.names = TRUE, ...)
# S3 method for matrix
fprod(x, g = NULL, w = NULL, TRA = NULL, na.rm = .op[["na.rm"]],
use.g.names = TRUE, drop = TRUE, ...)
# S3 method for data.frame
fprod(x, g = NULL, w = NULL, TRA = NULL, na.rm = .op[["na.rm"]],
use.g.names = TRUE, drop = TRUE, ...)
# S3 method for grouped_df
fprod(x, w = NULL, TRA = NULL, na.rm = .op[["na.rm"]],
use.g.names = FALSE, keep.group_vars = TRUE,
keep.w = TRUE, stub = .op[["stub"]], ...)
The (w weighted) product of x, grouped by g, or (if TRA is used) x transformed by its (grouped, weighted) product.
a numeric vector, matrix, data frame or grouped data frame (class 'grouped_df').
a factor, GRP object, atomic vector (internally converted to factor) or a list of vectors / factors (internally converted to a GRP object) used to group x.
a numeric vector of (non-negative) weights, may contain missing values.
an integer or quoted operator indicating the transformation to perform:
0 - "na" | 1 - "fill" | 2 - "replace" | 3 - "-" | 4 - "-+" | 5 - "/" | 6 - "%" | 7 - "+" | 8 - "*" | 9 - "%%" | 10 - "-%%". See TRA.
logical. Skip missing values in x. Defaults to TRUE and implemented at very little computational cost. If na.rm = FALSE a NA is returned when encountered.
logical. Make group-names and add to the result as names (default method) or row-names (matrix and data frame methods). No row-names are generated for data.table's.
matrix and data.frame method: Logical. TRUE drops dimensions and returns an atomic vector if g = NULL and TRA = NULL.
grouped_df method: Logical. FALSE removes grouping variables after computation.
grouped_df method: Logical. Retain product of weighting variable after computation (if contained in grouped_df).
character. If keep.w = TRUE and stub = TRUE (default), the weights column is prefixed by "prod.". Users can specify a different prefix through this argument, or set it to FALSE to avoid prefixing.
arguments to be passed to or from other methods. If TRA is used, passing set = TRUE will transform data by reference and return the result invisibly.
Non-grouped product computations internally utilize long-doubles in C, for additional numeric precision.
The weighted product is computed as prod(x * w), using a single pass in C. If na.rm = TRUE, missing values will be removed from both x and w i.e. utilizing only x[complete.cases(x,w)] and w[complete.cases(x,w)].
For further computational details see fsum, which works equivalently.
fsum, Fast Statistical Functions, Collapse Overview
## default vector method
mpg <- mtcars$mpg
fprod(mpg) # Simple product
fprod(mpg, w = mtcars$hp) # Weighted product
fprod(mpg, TRA = "/") # Simple transformation: Divide by product
fprod(mpg, mtcars$cyl) # Grouped product
fprod(mpg, mtcars$cyl, mtcars$hp) # Weighted grouped product
fprod(mpg, mtcars[c(2,8:9)]) # More groups..
g <- GRP(mtcars, ~ cyl + vs + am) # Precomputing groups gives more speed !
fprod(mpg, g)
fprod(mpg, g, TRA = "/") # Groupwise divide by product
## data.frame method
fprod(mtcars)
head(fprod(mtcars, TRA = "/"))
fprod(mtcars, g)
fprod(mtcars, g, use.g.names = FALSE) # No row-names generated
## matrix method
m <- qM(mtcars)
fprod(m)
head(fprod(m, TRA = "/"))
fprod(m, g) # etc..
## method for grouped data frames - created with dplyr::group_by or fgroup_by
mtcars |> fgroup_by(cyl,vs,am) |> fprod()
mtcars |> fgroup_by(cyl,vs,am) |> fprod(TRA = "/")
mtcars |> fgroup_by(cyl,vs,am) |> fselect(mpg) |> fprod()
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