Line plots

Introduction to Data Visualization with ggplot2

Rick Scavetta

Founder, Scavetta Academy

Common plot types

Plot type	Possible Geoms
Scatter plots	points, jitter, abline, smooth, count
Bar plots	histogram, bar, col, errorbar
Line plots	line, path

Beaver

str(beaver)

'data.frame':    101 obs. of  3 variables:
 $ time  : POSIXct, format: "2000-01-01 09:30:00" "2000-01-01 09:40:00" "2000-01-01 09:50:00" ...
 $ temp  : num  36.6 36.7 36.9 37.1 37.2 ...
 $ active: Factor w/ 2 levels "0","1": 1 1 1 1 1 1 1 1 1 1 ...

Beaver

ggplot(beaver, aes(x = time, y = temp)) +
  geom_line()

Beaver

ggplot(beaver, aes(x = time, y = temp, 
                   color = factor(active))
                   ) +
  geom_line()

The fish catch dataset

str(fish)

'data.frame':    427 obs. of  3 variables:
 $ Species: Factor w/ 7 levels "Pink","Chum",..: 1 2 3 4 5 6 7 1 2 3 ...
 $ Year   : int  1950 1950 1950 1950 1950 1950 1950 1951 1951 1951 ...
 $ Capture: int  100600 139300 64100 30500 0 23200 10800 259000 155900 51200 ...

Linetype aesthetic

ggplot(fish, aes(x = Year, 
                 y = Capture, 
                 linetype = Species)) + 
  geom_line()

Size aesthetic

ggplot(fish, aes(x = Year, 
                 y = Capture, 
                 size = Species)) + 
  geom_line()

Color aesthetic

ggplot(fish, aes(x = Year, 
                 y = Capture, 
                 color = Species)) + 
  geom_line()

Aesthetics for categorical variables

Fill aesthetic with geom_area()

ggplot(fish, aes(x = Year, 
                 y = Capture, 
                 fill = Species)) + 
  geom_area()

Using position = "fill"

ggplot(fish, aes(x = Year, 
                 y = Capture, 
                 fill = Species)) + 
  geom_area(position = "fill")

geom_ribbon()

ggplot(fish, aes(x = Year, 
                 y = Capture, 
                 fill = Species)) + 
  geom_ribbon(aes(ymax = Capture, 
                  ymin = 0), 
              alpha = 0.3)

Let's practice!

Introduction to Data Visualization with ggplot2