points + lines

load packages

library(tidyverse)

## ── Attaching packages ─────────────────────────────────────── tidyverse 1.3.0 ──

## ✓ ggplot2 3.3.3     ✓ purrr   0.3.4
## ✓ tibble  3.1.0     ✓ dplyr   1.0.5
## ✓ tidyr   1.1.2     ✓ stringr 1.4.0
## ✓ readr   1.4.0     ✓ forcats 0.5.1

## ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
## x dplyr::filter() masks stats::filter()
## x dplyr::lag()    masks stats::lag()

library(palmerpenguins)

get penguin data

penguins <- penguins

geom_point + geom_line

Why do the points not join?

penguins %>%
  group_by(species) %>%
  summarise(mean = mean(body_mass_g, na.rm = TRUE)) %>%
  ggplot(aes(x = species, y = mean)) +
  geom_point() +
  geom_line()

## geom_path: Each group consists of only one observation. Do you need to adjust
## the group aesthetic?

need to specify a group aesthetic

penguins %>%
  group_by(species) %>%
  summarise(mean = mean(body_mass_g, na.rm = TRUE)) %>%
  ggplot(aes(x = species, y = mean, group = "species")) +
  geom_point() +
  geom_line()