How to create a column that records how many times a person

I want to create a column called visit_occurrance that sums the number of times each person_id reappears in the dataset. For example,

> dput(df)
structure(list(Person_ID = c(123L, 123L, 110L, 145L, 345L, 345L, 
345L, 345L, 300L, 234L, 234L, 111L, 110L)), class = "data.frame", row.names = c(NA, 
-13L))

Desired output:

> dput(df)
structure(list(Person_ID = c(123L, 123L, 110L, 145L, 345L, 345L, 
345L, 345L, 300L, 234L, 234L, 111L, 110L), Visit_occurrance = c(1L, 
2L, 1L, 1L, 1L, 2L, 3L, 4L, 1L, 1L, 2L, 1L, 2L)), class = "data.frame", row.names = c(NA, 
-13L))

CodePudding user response：

library(dplyr)
                                                                                                             -13L))
df %>% 
  group_by(Person_ID) %>% 
  mutate(Visit_occurrance = row_number())

   Person_ID Visit_occurrance
       <int>            <int>
 1       123                1
 2       123                2
 3       110                1
 4       145                1
 5       345                1
 6       345                2
 7       345                3
 8       345                4
 9       300                1
10       234                1
11       234                2
12       111                1
13       110                2