count {tidySingleCellExperiment}

R Documentation

Count observations by group

Description

count() lets you quickly count the unique values of one or more variables: df %>% count(a, b) is roughly equivalent to df %>% group_by(a, b) %>% summarise(n=n()). count() is paired with tally(), a lower-level helper that is equivalent to df %>% summarise(n=n()). Supply wt to perform weighted counts, switching the summary from n=n() to n=sum(wt).

add_count() are add_tally() are equivalents to count() and tally() but use mutate() instead of summarise() so that they add a new column with group-wise counts.

Usage

count(
  x,
  ...,
  wt = NULL,
  sort = FALSE,
  name = NULL,
  .drop = group_by_drop_default(x)
)

add_count(
  x,
  ...,
  wt = NULL,
  sort = FALSE,
  name = NULL,
  .drop = group_by_drop_default(x)
)

## Default S3 method:
add_count(
  x,
  ...,
  wt = NULL,
  sort = FALSE,
  name = NULL,
  .drop = group_by_drop_default(x)
)

## S3 method for class 'SingleCellExperiment'
add_count(
  x,
  ...,
  wt = NULL,
  sort = FALSE,
  name = NULL,
  .drop = group_by_drop_default(x)
)

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 to group by.
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.
.drop	For count(): if FALSE will include counts for empty groups (i.e. for levels of factors that don't exist in the data). Deprecated in add_count() since it didn't actually affect the output.

Value

An object of the same type as .data. count() and add_count() group transiently, so the output has the same groups as the input.

Examples

`%>%` <- magrittr::`%>%`
pbmc_small %>%

    count(groups)

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