remove rows if it is negative number

Question

If my data.frame looks like:

   A     B       C
1 10 James    Math
2 -1  Tony Science
3 -5 Kevin    Math
4 11 Chris    Math
5 13   Min English

I want to remove rows if the value of A has a negative number like this:

   A     B       C
1 10 James    Math
4 11 Chris    Math
5 13   Min English

Answer 1

Try this:

df <- df[df$A >= 0, ]