Conditional count with zero with dplyr
Solution 1:
You may first summarise the data to count number of Tool "A" in each ID and then count the counts.
library(dplyr)
df %>%
group_by(ID) %>%
summarise(ToolA = sum(Tool == "A")) %>%
count(ToolA, name = "count")
# ToolA count
# <int> <int>
#1 0 1
#2 1 3
#3 2 1