calculating counts and percentages of a variable

February 11, 2022

I am trying to create a count of the number of observations and extract percentages from those counts.

I have data that looks like this:

UserID              substance_use                     
43124                       0 
43124                       1
43124                       0 
43124                       0
43124                       1
215                         1
215                         1

I want a count of the total observations of substance use like this:

UserID             substance_use                                 count  
43124                       0                                        5
43124                       1                                        5
43124                       0                                        5
43124                       0                                        5
43124                       1                                        5
215                         1                                        2
215                         1                                        2

And then, I want the % of visits that participants said yes and no, like this:

UserID      substance_use      count      percent_yes       percent_no
43124        0                  5            40%               60%
43124        1                  5            40%               60%
43124        0                  5            40%               60%
43124        0                  5            40%               60%         
43124        1                  5            40%              0%  
215          1                  2            100%              0
215          1                  2            100%              0%

I tried using the count function for the first part, but it’s not taking into account the 0’s. Any help would be greatly appreciated.

>Solution :

We may use add_count to create the ‘count’ column and then get the mean of the binary column by group to return the percent_yes and subtract 100 from the percent_yes to return percent_no

library(dplyr)
df1 %>%
  add_count(UserID, name = 'count') %>%
  group_by(UserID) %>%
  mutate(percent_yes = 100 * mean(substance_use), 
       percent_no = 100 - percent_yes) %>% 
  ungroup

-output

# A tibble: 7 × 5
  UserID substance_use count percent_yes percent_no
   <int>         <int> <int>       <dbl>      <dbl>
1  43124             0     5          40         60
2  43124             1     5          40         60
3  43124             0     5          40         60
4  43124             0     5          40         60
5  43124             1     5          40         60
6    215             1     2         100          0
7    215             1     2         100          0

NOTE: Here, we assumed no missing values in ‘substance_use’ column

data

df1 <- structure(list(UserID = c(43124L, 43124L, 43124L, 43124L, 43124L, 
215L, 215L), substance_use = c(0L, 1L, 0L, 0L, 1L, 1L, 1L)), 
class = "data.frame", row.names = c(NA, 
-7L))