How to get the means of all columns but one?
问题 I have a data like below : > dplyr::tbl_df(sbp) Country X1980 X1981 X1982 X1983 X1984 X1985 Albania 132.9270 133.0296 133.1459 133.1868 133.2048 133.2577 Algeria 132.4093 132.1710 131.9649 131.7835 131.6161 131.4345 Andorra 140.8585 140.1076 139.3727 138.6457 137.9525 137.3192 I want to get mean of values for each year for all countries and add a row like World to the end of the dataframe, so that I can plot the change of the mean value through years, in that format. I tried using gather() so