dataframe - Two equal max values in R -

i have dataframe numbers(score) , repeating id. want maximum value each of id. used function

top = aggregate(df$score, list(df$id),max)

this returned me top dataframe maximum values corresponding each id.

but happens 1 of id, have 2 equal max value. function ignoring second value.

is there way retain both max values.?

for example:

id   score 1    12 1    15 1    1 1    15 2    23 2    12 2    13

the above function gives me this: top

id    score 1     15 2     23

i need this: top

id   score 1    15 1    15 2    23

i recommend data.table chris mentioned (good speed, steeper learning curve). or if don't want data.table use plyr:

library(plyr) ddply(df, .(id), subset, score==max(score)) # same ddply(df, .(id), function (x) subset(x, score==max(score)))

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