Bar Charts in ggplot With Multiple Outcomes

Setup

library(ggplot2) # beautiful graphs

library(tidyr) # tidy data

Simulated Data

x <- c(1, 2, 3) # independent variable

y <- c(4, 5, 6) # first outcome

z <- c(7, 8, 3) # second outcome

mydata <- tibble(x, y, z)

mydata # replay mydata

# A tibble: 3 × 3
      x     y     z
  <dbl> <dbl> <dbl>
1     1     4     7
2     2     5     8
3     3     6     3

Reshape Data With pivot_longer

myReshapedData <- mydata %>% 
  pivot_longer(c(y, z), # values to pivot or reshape
               names_to = "newnames", # names will be
               values_to = "newvalues") # values will be

myReshapedData # replay myReshapedData

# A tibble: 6 × 3
      x newnames newvalues
  <dbl> <chr>        <dbl>
1     1 y                4
2     1 z                7
3     2 y                5
4     2 z                8
5     3 y                6
6     3 z                3

Graphs

Bar Chart With Stacked Bars

geom_bar()

ggplot(myReshapedData, # data I am using
       aes(x = x, # x is newnames
           y = newvalues, # y is newvalues
           fill = newnames)) + # fill is newnames
  geom_bar(stat = "identity") # y is actual bar height

geom_col()

By default, geom_col() assumes stat = 'identity' i.e. y is the height of the bar.

ggplot(myReshapedData, # data I am using
       aes(x = x, # x is newnames
           y = newvalues, # y is newvalues
           fill = newnames)) + # fill is newnames
  geom_col() # y is actual bar height

Bar Chart With Unstacked Bars

ggplot(myReshapedData, # data I am using
       aes(x = x, # x is newnames
           y = newvalues, # y is newvalues
           fill = newnames)) + # fill is newnames
  geom_bar(stat = "identity", # y is actual bar height
           position = position_dodge()) # unstack bars

Line Chart

ggplot(myReshapedData, # data I am using
       aes(x = x, # x is x
           y = newvalues, # y is value
           color = newnames, # color is key
           group = newnames)) + # line needs a group aesthetic
  geom_line()