aggregate in sf

[GreenStat]

Hi,
not sure if this is an error, bug or lack of documentation ....

with this sf object

library(sf)
library(tidyverse)

data(meuse, package = "sp")
meuse_sf = st_as_sf(meuse, coords = c("x", "y"), crs = 28992, agr = "constant")
#  
meuse_sf %>% str
# suppresed output

I tried aggregate with several options:

meuse_sf %>% aggregate(by=list(meuse_sf$soil))
Error in match.fun(FUN) : argument "FUN" is missing, with no default
#oke we need FUN

meuse_sf %>% aggregate(by=list(meuse_sf$soil), FUN="first")
Error in aggregate.data.frame(x, list(Group.1 = by), FUN, ..., simplify = FALSE) : 
  arguments must have same length

I also tried other options for FUN (mean, max etc) and with 'union=TRUE' but nothing seems to work

NB in sp this works

aggregate(as(meuse_sf,'Spatial'),by=list(meuse_sf$soil), FUN="first") 

Any thoughts ?

[Nowosad]

What do you think about this solution:

aggregate_meuse_sf <- meuse_sf %>% 
        group_by(soil) %>% 
        summarise()

[edzer]

Hi!
yeah, the sf behavior was (documented) such that by=meuse_sf$soil would have worked, without the list(). Since the list() is in line with stats::aggregate (and sp::aggregate), I now changed code such that a list is required (and hence multiple aggregation predicates can be defined). Thanks!

[Nowosad]

@edzer Is there a reason to name this function aggregateand not st_aggregate?

[edzer]

Yes: it is not a function but a method (aggregate.sf) for an existing function (stats::aggregate). We also don't write a st_subset when writing a method for [.