dbplyr: count.tbl_lazy – R documentation

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count.tbl_lazy

Count observations by group

Description

These are methods for the dplyr count() and tally() generics. They wrap up group_by.tbl_lazy(), summarise.tbl_lazy() and, optionally, arrange.tbl_lazy().

Usage

## S3 method for class 'tbl_lazy'
count(x, ..., wt = NULL, sort = FALSE, name = NULL)

## S3 method for class 'tbl_lazy'
tally(x, wt = NULL, sort = FALSE, name = NULL)

Arguments

`x`	A data frame, data frame extension (e.g. a tibble), or a lazy data frame (e.g. from dbplyr or dtplyr).
`...`	<`data-masking`> Variables, or functions of variables. Use `desc()` to sort a variable in descending order.
`wt`	<`data-masking`> Frequency weights. Can be `NULL` or a variable: If `NULL` (the default), counts the number of rows in each group. If a variable, computes `sum(wt)` for each group.
`sort`	If `TRUE`, will show the largest groups at the top.
`name`	The name of the new column in the output. If omitted, it will default to `n`. If there's already a column called `n`, it will error, and require you to specify the name.

Examples

library(dplyr, warn.conflicts = FALSE)

db <- memdb_frame(g = c(1, 1, 1, 2, 2), x = c(4, 3, 6, 9, 2))
db %>% count(g) %>% show_query()
db %>% count(g, wt = x) %>% show_query()
db %>% count(g, wt = x, sort = TRUE) %>% show_query()

dbplyr

A 'dplyr' Back End for Databases

v2.1.1

MIT + file LICENSE

Authors

Hadley Wickham [aut, cre], Maximilian Girlich [aut], Edgar Ruiz [aut], RStudio [cph, fnd]

Initial release