[R] Merging two data files based on common dates

Hello there Pardon my ignorance but, I have two data files with different series of dates and x and y values. There are common dates in both files. For example >datafile1 date1 xval 31/12/1982 20 1/01/198330 2/01/198340 3/01/198350 4/

[R] Summing daily data for each year

Hello there I have a DAILY data set (as shown below) with Date and Streamflow from April 1995 to Aug 2006. I want a yearly sum the streamflow value (for each year - first and last incomplete year). Does anyone know how to do this in R? I have tried everything I could think of, e.g. importe

[R] Summing daily data for each year

Hello there I have a DAILY data set (as shown below) with Date and Streamflow from April 1995 to Aug 2006. I want a yearly sum the streamflow value (for each year - first and last incomplete year). Does anyone know how to do this in R? I have tried everything I could think of, e.g. i