r - Aggregate data with custom group function -

r - Aggregate data with custom group function -

i have info frame , want apply aggregate function on of it's columns value, grouping them custom key.

i have custom function takes input row of info frame , generates key. how can phone call aggregate function (or sapply, tapply...)

something basically:

getrowkey <- function(row_value) { getrowkey = row_value[1] % 5 } aggregate(my_data, getrowkey, fun=max)

with input this:

1,1 6,2 1,3 7,3 12,5 11,8

i'll have next results:

1,8 2,5

in r, should utilize %%, not single % symbol. in opinion, don't need custom function here. it's easier substitute function body straight aggregate() function.

> d <- read.table(text = "1,1 6,2 1,3 7,3 12,5 11,8", sep = ",") > aggregate(d[[2]], d[1] %% 5, max) # v1 x # 1 1 8 # 2 2 5

as stands, custom function not homecoming anything. if adjust

> getrowkey <- function(row_value) { row_value[1] %% 5 }

we can utilize in aggregate() follows,

> aggregate(dat[[2]], getrowkey(dat[1]), max) v1 x 1 1 8 2 2 5

r group aggregate-functions