code used in my dplyr talk at e-Rum 2020

dplyr_erum.R

library(dplyr, warn.conflicts = FALSE)
library(palmerpenguins)

# multiple rows
penguins %>%
  group_by(species) %>%
  summarise(
    prob = c(.25, .75),
    length = quantile(bill_length_mm, prob, na.rm = TRUE),
    depth = quantile(bill_depth_mm, prob, na.rm = TRUE)
  )

# multiple columns
penguins %>%
  group_by(species) %>%
  summarise(
    broom::tidy(lm(bill_depth_mm ~ bill_length_mm))
  )

# working across() columns
penguins %>%
  group_by(species) %>%
  summarise(
    across(starts_with("bill"), min, na.rm = TRUE)
  )

# working across() columns
penguins %>%
  group_by(species) %>%
  summarise(
    across(starts_with("bill"),
           list(min = min, max = max),
           na.rm = TRUE
    )
  )

# .groups =
penguins %>%
  group_by(species, island) %>%
  summarise(
    prob = c(.25, .75),
    length = quantile(bill_length_mm, prob, na.rm = TRUE),
    depth = quantile(bill_depth_mm, prob, na.rm = TRUE)
  )

penguins %>%
  group_by(species, island) %>%
  summarise(
    length = mean(bill_length_mm, na.rm = TRUE),
    depth = mean(bill_depth_mm, na.rm = TRUE)
  )


penguins %>%
  group_by(species, island) %>%
  summarise(
    length = mean(bill_length_mm, na.rm = TRUE),
    depth = mean(bill_depth_mm, na.rm = TRUE)
  )

# .groups = drop
penguins %>%
  group_by(species, island) %>%
  summarise(.groups = "drop",
    length = mean(bill_length_mm, na.rm = TRUE),
    depth = mean(bill_depth_mm, na.rm = TRUE)
  )

# .groups = keep
penguins %>%
  group_by(species, island) %>%
  summarise(.groups = "keep",
    length = mean(bill_length_mm, na.rm = TRUE),
    depth = mean(bill_depth_mm, na.rm = TRUE)
  )