Count multiple rows in dataframe in R

Question

I have a dataframe (classification of substances with the classes) in the following format:

1	2	3	4
Organic compounds	Benzenoids	Benzene	NA
Organic compounds	Benzenoids	Benzene	NA
Organic compounds	Organic oxygen compounds	NA	NA
NA	NA	NA	NA
Organic compounds	Benzenoids	NA	NA

I need to add a new column with the count of the rows with the same value in all 4 columns (rows with same value in column 1-4):

1	2	3	4	count
Organic compounds	Benzenoids	Benzene	NA	2
Organic compounds	Organic oxygen compounds	NA	NA	1
NA	NA	NA	NA	1
Organic compounds	Benzenoids	NA	NA	1

My problem is, to add a new column in the dataframe, which count the amount of multiple rows (1-4) at the same time.

For 1 row I have used table():

data.frame(table(df$"1")

But if I use more than one row, there is not the right output data.frame(table(df$"1",df$"2",df$"3", df$"4")).

I also tried it with count()

I found no solution for this specific problem here. So I need your help, please. Thanks!

Answer 1

You can easily do this with dplyr:

library(dplyr)

df %>%
   count(`1`, `2`, `3`, `4`)