count.tbl_lazy: Count observations by group

In dbplyr: A 'dplyr' Back End for Databases

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'
add_count(x, ..., wt = NULL, sort = FALSE, name = NULL, .drop = 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 use nn. If there's a column called n and nn, it'll use nnn, and so on, adding ns until it gets a new name.
.drop	Not supported for lazy tables.

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 documentation built on May 29, 2024, 6:19 a.m.