R coding: How to keep records with 4 complete quarters of data

Question

I have a dataframe with company quarterly data and have this question:

How can I retain records for only those companies with 4 quarters of data (as companies sometimes

Answer 1

The following code can help you ....

final=data.frame()
for(i in unique(data$company)){
temp=data[data$company==i,]
for(j in unique(temp$year)){
    if(nrow(temp[temp$year==j,])==4)
        final=rbind(final,data.frame(company=i,Year=j))
}
}

'final' dataframe will contain your required fields.