tell us

count() allows you to quickly count the number of unique values of one or more variables. While it seems similar to tally(), tally() only allows you to count within an already defined group, while count() allows you to define and group variables within the function.

show us

write a little demo to show how to install/load the package and use the function on some real data ### install and load packages

library(tidyverse)
## -- Attaching packages --------------------------------------- tidyverse 1.3.1 --
## v ggplot2 3.3.3     v purrr   0.3.4
## v tibble  3.1.2     v dplyr   1.0.6
## v tidyr   1.1.3     v stringr 1.4.0
## v readr   1.4.0     v forcats 0.5.1
## -- Conflicts ------------------------------------------ tidyverse_conflicts() --
## x dplyr::filter() masks stats::filter()
## x dplyr::lag()    masks stats::lag()
library(palmerpenguins)

get some data

data <- penguins

use the function

Here is an example showing how count() allows you to group the data within the function, whereas with tally() you need to group your variables separately.

count(data, species)
## # A tibble: 3 x 2
##   species       n
##   <fct>     <int>
## 1 Adelie      152
## 2 Chinstrap    68
## 3 Gentoo      124
data %>% count(species, sort = TRUE)
## # A tibble: 3 x 2
##   species       n
##   <fct>     <int>
## 1 Adelie      152
## 2 Gentoo      124
## 3 Chinstrap    68
tally(data)
## # A tibble: 1 x 1
##       n
##   <int>
## 1   344
data <- data %>% 
  group_by(species)
tally(data, sort = TRUE)
## # A tibble: 3 x 2
##   species       n
##   <fct>     <int>
## 1 Adelie      152
## 2 Gentoo      124
## 3 Chinstrap    68

more resources

write a little paragraph about how you learned about the function- what did you google? Include a list of the documentation that you found useful andresources that someone learning about the function might need. If you can find pictures or memes to include, great!!

count() 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). Documentation here