Combining geom_bar with geom_line in one plot

Question

I have tried to combine 2 plots into 1 plot. But the geom_line doesn't show up and, the y-axis to the right is not in %.

The geom_bar shows what i want it to, but the geom_line does not show up in the ggplot. The geom_line is a %, and shows the relationship between BV and FV, % = BG/FV.

My table as it looks like in Excel.

Comma for Europeans:

Aar	Type	mia_kr	BG
2004	FV	1918050	0,489221
2004	BG	938350,0583
2005	FV	2312210	0,447918
2005	BG	1035680,125
2006	FV	2842071	0,416046
2006	BG	1182431,742
2007	FV	2910107	0,447245
2007	BG	1301530,525

All those who doesn't use comma:

Aar	Type	mia_kr	BG
2004	FV	1918050	0.489221
2004	BG	938350.0583
2005	FV	2312210	0.447918
2005	BG	1035680.125
2006	FV	2842071	0.416046
2006	BG	1182431.742
2007	FV	2910107	0.447245
2007	BG	1301530.525

My code:

    library(ggplot2)
SAMLET <- data.frame(Aar=c(2004, 2004, 2005, 2005, 2006, 2006, 2007, 2007),
                  Type=c(FV, BG, FV, BG,FV, BG,FV, BG,),
                  mia_kr=c(1918050,938350.0583, 2312210, 1035680.125, 2842071, 1182431.742, 2910107, 1301530.525))
SAMLET_2 <- data.frame(Aar=c(2004, 2005, 2006, 2007,),
BG=c(0.489221, ,0.447918, ,0.416046, , 0.447245, ))



ggplot() + 
  geom_bar(mapping = aes(x= SAMLET$Aar, y= SAMLET$mia_kr, fill = SAMLET$Type), stat="identity",position = "identity")+
  geom_line(mapping = aes(x= SAMLET_2$Aar, y = SAMLET_2$BG),size = 2, color = "blue") +
  scale_y_continuous(labels = scales::format_format(big.mark = ".", decimal.mark = ",", scientific = FALSE),
                     sec.axis = sec_axis(~ ./4,labels = scales::format_format(big.mark = ".", decimal.mark = ",", scientific = FALSE) ))

Shows the barplots with 2 y-axis

How it should look like

Answer 1

you can try

ggplot(df, aes(x = Aar)) + 
   geom_col(aes(y = mia_kr, fill = Type)) + 
   geom_line(aes(y = BG*max(mia_kr), group =Type))  +
   scale_y_continuous(labels = scales::format_format(big.mark = ".", decimal.mark = ",", scientific = FALSE),
                     sec.axis = sec_axis(~ ./max(df$mia_kr)))

Note that the line values are upscaled according the max mia_kr value.