Interpolate / Extend quarterly to monthly series
问题 I have a data.frame that contains quarterly observations. I now want to interpolate monthly values (preferred cubic, linear is fine). The intermediate goal should be to create a data.frame with DATE as the index and missing values for all the monthly observations. Googling showed that I should create an empty data.frame for the whole time range and then merge it - but what ever I tried so far gave me errors. Here's my procedure; but since I'm a newb to r , I'm open to any suggestions for