[R] Different symbols for select points

Dear R users,  I hope you can help me as you have done before.  I was wondering if I can make some of the points on my graph a different colour and symbol? Some of my soil samples are enriched and I wanted them to be shown with a red triangle and the samples which are not enriched I wanted to s

[R] x axis

Dear R users, I am quite desperate for help. I haven't used R in a couple of years and I'm currently finishing a masters project and running out of time to figure out my problem. I have read and tried the examples on many websites, in your forums and R Help yet still can't manage to change the