How to plot combo plot in R using ggplot

Question

my data frame i am using is

the output I'm trying to achieve I achieved this output in excel and I'm trying to reproduce it in R but I am not able to get the 2 lines I tried using the code

ggplot(yearly_percentage) +
  geom_bar(aes(x=year, y=count_percentage, fill=member_casual), position = "dodge",stat = "identity") +
  geom_line( aes(x=year,y=ride_Length))

this is the output I get

here is my reproduceable sample of data frame

structure(list(year = c("2016", "2016", "2017", "2017", "2018", 
"2018", "2019", "2019", "2020", "2020"), member_casual = c("casual", 
"member", "casual", "member", "casual", "member", "casual", "member", 
"casual", "member"), count_percentage = c("23.88%", "76.12%", 
"21.86%", "78.14%", "18.79%", "81.21%", "23.06%", "76.94%", "11.31%", 
"88.69%"), ride_Length = c("45%", "55%", "42%", "58%", "46.6%", 
"53.4%", "51.5%", "48.5%", "42%", "58%")), class = c("tbl_df", 
"tbl", "data.frame"), row.names = c(NA, -10L))

Answer 1

As the message suggest you have to set the group aes and as you probably want colored lines you have to map on the color aes additionally. Also note, that your columns are not numerics but characters. Hence you have to convert them to numerics and instead format as percentages via the labels argument of scale_y_continuous :

library(ggplot2)

yearly_percentage$count_percentage <- readr::parse_number(yearly_percentage$count_percentage)
yearly_percentage$ride_Length <- readr::parse_number(yearly_percentage$ride_Length)

ggplot(yearly_percentage) +
  geom_bar(aes(x = year, y = count_percentage, fill = member_casual), position = "dodge", stat = "identity") +
  geom_line(aes(x = year, y = ride_Length, color = member_casual, group = member_casual)) +
  scale_y_continuous(labels = scales::label_percent(scale = 1))