Create a column based on another data frame

Question

I have what seems like a simple requirement, but I cannot achieve the desired result. My data is very large, so I just show a screenshot:

I want: if ps2c$ps == present2$pn then ps2c$sf == present2$sf .

If it’s not clear, for every ps2c$ps there is present2$pn (present2 is just average data).

Answer 1

You do not provide test data, but something like the following may work:

 ps2c$sf <- present2$sf[match(ps2c$ps, present2$pn)]