fcount: Efficiently Count Observations by Group

In collapse: Advanced and Fast Data Transformation

Efficiently Count Observations by Group

Description

A much faster replacement for dplyr::count.

Usage

fcount(x, ..., w = NULL, name = "N", add = FALSE,
      sort = FALSE, decreasing = FALSE)

fcountv(x, cols = NULL, w = NULL, name = "N", add = FALSE,
        sort = FALSE, ...)

Arguments

x	a data frame or list-like object, including 'grouped_df' or 'indexed_frame'. Atomic vectors or matrices can also be passed, but will be sent through qDF.
...	for fcount: names or sequences of columns to count cases by - passed to fselect. For fcountv: further arguments passed to GRP (such as decreasing, na.last, method, effect etc.). Leaving this empty will count on all columns.
cols	select columns to count cases by, using column names, indices, a logical vector or a selector function (e.g. is_categorical).
w	a numeric vector of weights, may contain missing values. In fcount this can also be the (unquoted) name of a column in the data frame. fcountv also supports a single character name. Note that the corresponding argument in dplyr::count is called wt, but collapse has a global default for weights arguments to be called w.
name	character. The name of the column containing the count or sum of weights. dplyr::count it is called "n", but "N" is more consistent with the rest of collapse and data.table.
add	TRUE adds the count column to x. Alternatively add = "group_vars" (or add = "gv" for parsimony) can be used to retain only the variables selected for counting in x and the count.
sort, decreasing	arguments passed to GRP affecting the order of rows in the output (if add = FALSE), and the algorithm used for counting. In general, sort = FALSE is faster unless data is already sorted by the columns used for counting.

Value

If x is a list, an object of the same type as x with a column (name) added at the end giving the count. Otherwise, if x is atomic, a data frame returned from qDF(x) with the count column added. By default (add = FALSE) only the unique rows of x of the columns used for counting are returned.

See Also

GRPN, fnobs, fndistinct, Fast Grouping and Ordering, Collapse Overview

Examples

fcount(mtcars, cyl, vs, am)
fcountv(mtcars, cols = .c(cyl, vs, am))
fcount(mtcars, cyl, vs, am, sort = TRUE)
fcount(mtcars, cyl, vs, am, add = TRUE)
fcount(mtcars, cyl, vs, am, add = "group_vars")

## With grouped data
mtcars |> fgroup_by(cyl, vs, am) |> fcount()
mtcars |> fgroup_by(cyl, vs, am) |> fcount(add = TRUE)
mtcars |> fgroup_by(cyl, vs, am) |> fcount(add = "group_vars")

## With indexed data: by default counting on the first index variable
wlddev |> findex_by(country, year) |> fcount()
wlddev |> findex_by(country, year) |> fcount(add = TRUE)
# Use fcountv to pass additional arguments to GRP.pdata.frame,
# here using the effect argument to choose a different index variable
wlddev |> findex_by(country, year) |> fcountv(effect = "year")
wlddev |> findex_by(country, year) |> fcountv(add = "group_vars", effect = "year")

collapse documentation built on Nov. 3, 2024, 9:08 a.m.