In R, how do I create a bar graph using a categorical x and the average of a numeric y with ggplot2?

Question

I am using R version 3.5.1.

I started with this problem , and used the code suggested by the top comment on my own dataset, where time_len is a categorical variable telling how long it takes to play game i, with values of short, medium, and long; num_fans is a numeric variable telling how many fans game i has:

ggplot(cdata) +
  aes(x = time_len, y = num_fans) +
  geom_bar(stat = "identity")

Here is the plot:

I created the bar chart using the code above, but the problem is that the num_fans variable looks like it is a total. I want it to show the average for each category.

EDIT: here is a sample of my data.

  game_id min_players single_player max_players family_game avg_time time_len year life avg_rating
1  161936           2         multi           4      family       60    short 2015    4    8.65105
2  187645           2         multi           4      family      240     long 2016    3    8.45420
3   12333           2         multi           2       small      180     long 2005   14    8.32843
4  193738           2         multi           4      family      150   medium 2016    3    8.28646
5  162886           1        single           4      family      120   medium 2017    2    8.39401
6   84876           2         multi           4      family       90   medium 2011    8    8.12803
  geek_rating   rating age owned num_fans
1     8.49375 8.572400  13 47498     2168
2     8.16391 8.309055  14 23989     1594
3     8.18051 8.254470  13 45955     3639
4     8.07144 8.178950  12 21513      835
5     7.96162 8.177815  13 13743     1002
6     8.01120 8.069615  12 49353     1866

Again, I am only asking about time_len. Is there a way to show the average of num_fans ?

Answer 1

Try replacing the

geom_bar(stat = "identity")

line with

stat_summary(geom = "bar", fun.y = "mean")?

(Note: this is the answer contributed by Z.Lin, who told me that I could post it as an answer.)