CODEWITHSUNDEEP
rmatrixcountdplyr
Sam
Sam

Reputation: 99

count occurences conditional on multiple other columns in r

Suppose I have a data frame where each person is represented as having a specific dose category (1-4) and specific followup category (1-7).

dose_followup = data.frame(
         dose = c(3,1,2,2,4,3,1,4,1,3,3,2,4,1,3,3),
         followup = c(2,4,2,1,6,2,7,3,6,3,5,5,6,4,2,2))

How can I count the number of co-occurrences and store them? For example, dose == 3 occurs with followup == 2 a total of 4 times. I want to make that count (i.e., 4) and either print it or store the value 4 in a matrix's cell corresponding to dose == 3 and followup == 2.

My actual dataframe is large, but it has only 4 dose categories and 7 followup categories. So the output matrix would be small.

I have tried various approaches with group_by() and with summarise() but without success. Thank you for any help.

Upvotes: 0

Views: 31

Answers (1)

Gregor Sturm
Gregor Sturm

Reputation: 2930

A simple table will do it:

table(dose_followup)

Result:

     followup
dose 1 2 3 4 5 6 7
   1 0 0 0 2 0 1 1
   2 1 1 0 0 1 0 0
   3 0 4 1 0 1 0 0
   4 0 0 1 0 0 2 0

If you insist doing it with tidyverse you can use

dose_followup %>% group_by(dose, followup) %>% summarise(n())

Result:

1.00     4.00     2
1.00     6.00     1
1.00     7.00     1
2.00     1.00     1
2.00     2.00     1
2.00     5.00     1
3.00     2.00     4
3.00     3.00     1
3.00     5.00     1
4.00     3.00     1
4.00     6.00     2

Upvotes: 1

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