{introverse} quick docs
dplyr::n()
get_help() docs
Description
The n() function is part of the {dplyr} package, which is part of the {tidyverse}.
The function n() is a helper function that returns a number representing the total number of rows in a given grouping. It is most useful if you want to add an ‘index column’ in a tibble (data frame).
To use this function, you need to either first load the {dplyr} library, or always use the function with dplyr::n() notation.
# Load the library
library(dplyr)
# Or, load the full tidyverse:
library(tidyverse)
# Or, use :: notation
dplyr::n()Conceptual Usage
tibble %>%
mutate(column_ranging_1_to_n = 1:n())Examples
The examples below use the carnivores dataset. Learn more about this dataset with get_help("carnivores").
# Show the carnivores dataset
carnivores## # A tibble: 9 × 4
## name genus awake brainwt
## <chr> <fct> <dbl> <dbl>
## 1 Arctic fox Vulpes 11.5 0.0445
## 2 Cheetah Acinonyx 11.9 NA
## 3 Dog Canis 13.9 0.07
## 4 Gray seal Haliochoerus 17.8 0.325
## 5 Jaguar Panthera 13.6 0.157
## 6 Lion Panthera 10.5 NA
## 7 Northern fur seal Callorhinus 15.3 NA
## 8 Red fox Vulpes 14.2 0.0504
## 9 Tiger Panthera 8.2 NA# Make a new column `one_to_n` that counts the rows 1-n in carnivores
carnivores %>%
mutate(one_to_n = 1:n())## # A tibble: 9 × 5
## name genus awake brainwt one_to_n
## <chr> <fct> <dbl> <dbl> <int>
## 1 Arctic fox Vulpes 11.5 0.0445 1
## 2 Cheetah Acinonyx 11.9 NA 2
## 3 Dog Canis 13.9 0.07 3
## 4 Gray seal Haliochoerus 17.8 0.325 4
## 5 Jaguar Panthera 13.6 0.157 5
## 6 Lion Panthera 10.5 NA 6
## 7 Northern fur seal Callorhinus 15.3 NA 7
## 8 Red fox Vulpes 14.2 0.0504 8
## 9 Tiger Panthera 8.2 NA 9
# Make a new column `one_to_n` that counts the rows in carnivores, but
# where the numbering restarts for each `genus` grouping
carnivores %>%
group_by(genus) %>%
mutate(one_to_n = 1:n()) %>%
# arranging by genus to make the output easier to see
arrange(genus)## # A tibble: 9 × 5
## # Groups: genus [6]
## name genus awake brainwt one_to_n
## <chr> <fct> <dbl> <dbl> <int>
## 1 Cheetah Acinonyx 11.9 NA 1
## 2 Northern fur seal Callorhinus 15.3 NA 1
## 3 Dog Canis 13.9 0.07 1
## 4 Gray seal Haliochoerus 17.8 0.325 1
## 5 Jaguar Panthera 13.6 0.157 1
## 6 Lion Panthera 10.5 NA 2
## 7 Tiger Panthera 8.2 NA 3
## 8 Arctic fox Vulpes 11.5 0.0445 1
## 9 Red fox Vulpes 14.2 0.0504 2