Creating a Layered Bar Chart in RStudio

[repatter]

Hello, I have the following dataset:

 Infection Type Observed Disease Incidence (% Infected Heads)

1 Bt0 (control) 0%
2 Bt0 (D-19) 41%
3 Bt0 (L-18) 67%
4 Bt0 (T-33) 67%
5 Bt0 (T-35) 63%
6 IDO444 (L-18) 0%
7 PI178210 (L-18) 76%
8 PI178210 (D-19) 0%
9 PI554120 (L-18) 0%
10 PI554120 (D-19) 45%
11 Rio Blanco (L-18) 0%
12 Rio Blanco (T-13) 0%
13 Rio Blanco (T-33) 0%
14 Rio Blanco (T-35) 100%
15 UI Sparrow (control) 0%
16 UI Sparrow (D-19) 0%
17 UI Sparrow (T-33) 0%
18 WA8268 (D-19) 18%
Expected Disease Incidence (% Infected Heads)
1 100%
2 100%
3 100%
4 100%
5 100%
6 0%
7 100%
8 0%
9 100%
10 100%
11 100%
12 100%
13 100%
14 100%
15 0%
16 0%
17 0%
18 100%

I want to layer the observed disease incidence over the expected disease incidence in a bar chart. Any ideas for how to do this? Stacking would be inappropriate for this dataset because it's not additive.

Thanks!

[FJCC]

Is this the sort of thing you are looking for?

library(ggplot2)

DF <- data.frame(Name = c("A", "A", "B", "B", "C", "C"),
                 Type = c("Expect", "Obs", "Expect", "Obs", "Expect", "Obs"),
                 Value = c(60, 40, 70, 65, 50, 20)) 
DF
#>   Name   Type Value
#> 1    A Expect    60
#> 2    A    Obs    40
#> 3    B Expect    70
#> 4    B    Obs    65
#> 5    C Expect    50
#> 6    C    Obs    20

ggplot(mapping = aes(fill = Type)) + 
  geom_col(aes(Name, Value), alpha = 0.5, data = filter(DF, Type == "Expect")) +
  geom_col(aes(Name, Value), alpha = 0.5, data = filter(DF, Type == "Obs"))

^{Created on 2019-12-22 by the reprex package (v0.3.0.9000)}