Fill missing values in the data.frame with the data from the same data frame
问题 I'm trying to backfill a fully outerjoined table with nearest preceding column data. The data frame I have looks like.. (No rows have both sides as NA and the table is sorted by date). date X Y 2012-07-05 00:01:19 0.0122 NA 2012-07-05 03:19:34 0.0121 NA 2012-07-05 03:19:56 0.0121 0.027 2012-07-05 03:20:31 0.0121 NA 2012-07-05 04:19:56 0.0121 0.028 2012-07-05 04:20:31 0.0121 NA 2012-07-05 04:20:50 0.0121 NA 2012-07-05 04:22:29 0.0121 0.027 2012-07-05 04:24:37 0.0121 NA 2012-07-05 20:48:45 0