Adding an “M” coordinate (dimension) to an sf object in R?

Question

Is there a way to add an "M" coordinate (dimension) to an sf object in R? As far as I can tell, currently, only the "Z" coordinate can be added using the "st_zm()" function.

Answer 1

I would use sfheaders:

pt <- sf::st_sf(st_sfc(st_point(cbind(1, 1))))
## convert to data frame
df <- sfheaders::sf_to_df(pt)
df$m <- 0  ## add M
sfheaders::sf_pt(df)
  Simple feature collection with 1 feature and 0 fields
  geometry type:  POINT
  dimension:      XYM
  ...

You'll have to carry the crs over (use st_crs()<-) and handle other fields, but you can use sfheaders::sfc_* functions to create just the geometry column, and replace that.