New syntax to translate geometry N by values N? #2499
Description
As previously discussed in #903 (comment), the behavior of affine transformations is not homogeneous depending on the operation:
- translating with a vector of length two translate all geometries with these two values
- scaling with a vector of length N scales geometry N by value N
Would it be possible to add another syntax, e.g. st_geometry(*) + list(<vector>, <vector>) that would translate geometry N by values N? This would make more straightforward to translate geometries in a data frame using data from other columns. One additional question is how vectors of length one should be treated (i.e. recycle or throw an error).
To Reproduce
library(sf) nc <- st_read(system.file("shape/nc.shp", package = "sf")) ncg <- st_geometry(nc) plot(ncg, border = "grey") # scale cntrd <- st_centroid(ncg) ncg2 <- (ncg - cntrd) * nc$AREA + cntrd plot(ncg2, col = "blue", add = TRUE) # translate nc$move_east <- ifelse(nc$AREA > median(nc$AREA), 1, -1) nc$move_north <- ifelse(nc$AREA > median(nc$AREA), 2, -2) ncg[] <- Map(\(obj, x, y) obj + c(x, y), ncg, nc$move_east, nc$move_north) # or with the new syntax proposed here: # ncg <- ncg + list(nc$move_east, nc$move_north) plot(ncg, col = "red", add = TRUE)
Paste the output of your `sessionInfo()` and `sf::sf_extSoftVersion()`
sessionInfo() # R version 4.4.0 (2024-04-24 ucrt) # Platform: x86_64-w64-mingw32/x64 # Running under: Windows 10 x64 (build 19045) # # Matrix products: default # # # locale: # [1] LC_COLLATE=French_France.utf8 LC_CTYPE=French_France.utf8 LC_MONETARY=French_France.utf8 LC_NUMERIC=C # [5] LC_TIME=French_France.utf8 # # time zone: Europe/Paris # tzcode source: internal # # attached base packages: # [1] stats graphics grDevices utils datasets methods base # # other attached packages: # [1] sf_1.0-19 # # loaded via a namespace (and not attached): # [1] compiler_4.4.0 magrittr_2.0.3 class_7.3-22 s2_1.1.7 DBI_1.2.2 tools_4.4.0 # [7] units_0.8-5 proxy_0.4-27 rstudioapi_0.17.1 wk_0.9.4 Rcpp_1.0.12 KernSmooth_2.23-24 # [13] grid_4.4.0 e1071_1.7-14 classInt_0.4-11 sf::sf_extSoftVersion() # GEOS GDAL proj.4 GDAL_with_GEOS USE_PROJ_H PROJ # "3.12.2" "3.9.3" "9.4.1" "true" "true" "9.4.1"