[R] groups Rank

[Ragia Ibrahim]

Dear Group,kinldy, I have the following data frame df
         id value1           1  4   2           1  4   3           1  6   4           1  6   5           2  1.5   6           2  2.5  7           2  2.5   8           2  2.5  

add rank column regarding id coulmn where rank for the highest value would be 1, others rank would be the (value/ value of heighest)/ number of rows that took the same value
thus the data frame should be
        id value                    Rank1           1  4                    0.332           1  4                    0.333           1  6                    0.54           1  6                    0.55           2  1.5                  0.6   6           2  2.5                  0.337           2  2.5                  0.338           2  2.5                  0.33

how to reach this resultthanks in advanceRagia 		 	   		   		 	   		   		 	   		  
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