Summarizing with dplyr
Packages
library(tidyverse)
Load iris data set
data("iris")
head(iris)
## Sepal.Length Sepal.Width Petal.Length Petal.Width Species
## 1 5.1 3.5 1.4 0.2 setosa
## 2 4.9 3.0 1.4 0.2 setosa
## 3 4.7 3.2 1.3 0.2 setosa
## 4 4.6 3.1 1.5 0.2 setosa
## 5 5.0 3.6 1.4 0.2 setosa
## 6 5.4 3.9 1.7 0.4 setosa
summarise: to summarize only a single column
iris %>% group_by(Species) %>% summarise(mean(Sepal.Length))
## # A tibble: 3 × 2
## Species `mean(Sepal.Length)`
## <fct> <dbl>
## 1 setosa 5.01
## 2 versicolor 5.94
## 3 virginica 6.59
summarise_all: to summarize all columns
iris %>% group_by(Species) %>% summarise_all(.funs = c(mean="mean"))
## # A tibble: 3 × 5
## Species Sepal.Length_mean Sepal.Width_mean Petal.Length_mean Petal.Width_mean
## <fct> <dbl> <dbl> <dbl> <dbl>
## 1 setosa 5.01 3.43 1.46 0.246
## 2 versico… 5.94 2.77 4.26 1.33
## 3 virgini… 6.59 2.97 5.55 2.03
summarise_at: to summarize only certain columns
iris %>% group_by(Species) %>% summarise_at(
.vars = vars(Sepal.Length, Sepal.Width),
.funs = c(mean="mean"))
## # A tibble: 3 × 3
## Species Sepal.Length_mean Sepal.Width_mean
## <fct> <dbl> <dbl>
## 1 setosa 5.01 3.43
## 2 versicolor 5.94 2.77
## 3 virginica 6.59 2.97
summarise_if
iris %>% group_by(Species) %>%
summarise_if(.predicate = function(x) is.numeric(x),
.funs = funs(mean="mean"))
## Warning: `funs()` was deprecated in dplyr 0.8.0.
## ℹ Please use a list of either functions or lambdas:
##
## # Simple named list: list(mean = mean, median = median)
##
## # Auto named with `tibble::lst()`: tibble::lst(mean, median)
##
## # Using lambdas list(~ mean(., trim = .2), ~ median(., na.rm = TRUE))
## Call `lifecycle::last_lifecycle_warnings()` to see where this warning was
## generated.
## # A tibble: 3 × 5
## Species Sepal.Length_mean Sepal.Width_mean Petal.Length_mean Petal.Width_mean
## <fct> <dbl> <dbl> <dbl> <dbl>
## 1 setosa 5.01 3.43 1.46 0.246
## 2 versico… 5.94 2.77 4.26 1.33
## 3 virgini… 6.59 2.97 5.55 2.03
pass multiple functions
iris %>% group_by(Species) %>%
summarise_if(.predicate = function(x) is.numeric(x),
.funs = funs(mean="mean", Sd="sd"))
## Warning: `funs()` was deprecated in dplyr 0.8.0.
## ℹ Please use a list of either functions or lambdas:
##
## # Simple named list: list(mean = mean, median = median)
##
## # Auto named with `tibble::lst()`: tibble::lst(mean, median)
##
## # Using lambdas list(~ mean(., trim = .2), ~ median(., na.rm = TRUE))
## Call `lifecycle::last_lifecycle_warnings()` to see where this warning was
## generated.
## # A tibble: 3 × 9
## Species Sepal.Length_mean Sepal.Width_mean Petal.Length_mean Petal.Width_mean
## <fct> <dbl> <dbl> <dbl> <dbl>
## 1 setosa 5.01 3.43 1.46 0.246
## 2 versico… 5.94 2.77 4.26 1.33
## 3 virgini… 6.59 2.97 5.55 2.03
## # ℹ 4 more variables: Sepal.Length_Sd <dbl>, Sepal.Width_Sd <dbl>,
## # Petal.Length_Sd <dbl>, Petal.Width_Sd <dbl>
