merge data.frames based on year and fill in missing values

Question

I have two data.frames that I want to merge together. The first is:

datess <- seq(as.Date(\'2005-01-01\'), as.Date(\'2009-12-31\'), \'days\')
sample<-          


        

Answer 1

You can use match

matched<-match(format(sample$Date,"%Y"),a$a)
sample$y<-a$y[matched]
sample$Z<-a$Z[matched]