Count Data Frame Rows On Conditon for Arbitrary Columns in R

Question

I have a data frame with many columns. I need to get a list for arbitrary columns and the number of rows that meet some conditions based on those columns. For example, data frame has column a, b and c, I need to get row counts that b > 0 for b, and c > 0 for c in the form of

column count

b 23

c 12

What is the easiest way?

Answer 1

You could use lapply so that you don't need to repeat typing the same function for each column you want:

lapply(df[,c("b","c")], function(x) sum(x > 0)) 

In this case, you specify which columns you want the output for in the df[,c("b","c")] or you could replace that with just df to check all columns.

The output would be a list, which may be easier to handle than many separate values.

Answer 2

sum(df$b > 0)

sum(df$c > 0)