determine number of instances of a category in R

Question

This is my first time experimenting with R. I currently have a dataset called mydata that includes various categories. I need to somehow determine the number of ports that are equal to 80,443,25,993 out of all of the ports.

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Answer 1

When posting a question here it's always helpful to have a sample of the data you're using. You can do this easily with dput(head(data_frame)). Since you didn't provide that I can demonstrate counting for a given condition with the built-in demo data frame called mtcars. Here is how you'd count the number of observations (i.e., rows) with a cyl value of 4 or 6:

sum(mtcars$cyl %in% c(4, 6))

This works because mtcars$cyl %in% c(4, 6) returns a vector of logical values for each observation. The vector contains TRUE values for the matches (i.e., where the cyl variable contains either a 4 or a 6) and FALSE values otherwise.

mtcars$cyl %in% c(4, 6)
 [1]  TRUE  TRUE  TRUE  TRUE FALSE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE
[29] FALSE  TRUE FALSE  TRUE

Since R treats TRUE as 1 and FALSE as zero you can sum these values to find a total count.