count.tbl_lazy {dbplyr}R Documentation

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()

[Package dbplyr version 2.1.1 Index]