sf::st_transform() gives "crs not found" error

Question

I am using sf package version 0.9-6. I define a new object in ESRI:4326 and then try to reproject it to an Albers projection. I get an error, despite explicitly setting the crs when defining the object.

Here is MWE.

library(sf)
# Linking to GEOS 3.8.1, GDAL 3.1.4, PROJ 6.3.1
disp_win_wgs84 <- sf::st_sf(st_sfc(st_point(c(-97.2, 32.55)),
                         st_point(c(-85.55, 49.2)),
                         crs = 4326))
target_crs <- 102003
disp_win_trans <- sf::st_transform(disp_win_wgs84, crs = target_crs)

I get the following error:

Error in CPL_transform(x, crs, aoi, pipeline, reverse) : 
  crs not found: is it missing?
In addition: Warning message:
In CPL_crs_from_input(x) :
  GDAL Error 1: PROJ: proj_create_from_database: crs not found

Edit: updated to define the target_crs as a number. Apparently, this is what was causing the error (see the answer). The solution is to use target_crs <- "ESRI:102003", this does not raise an error.

Answer 1

What exactly is in target_crs? For example, using the USA Contiguous Albers Equal Area Conic ESRI projection (ESRI:102003), your code performs flawlessly:

disp_win_trans = sf::st_transform(
  disp_win_wgs84
  , crs = "ESRI:102003"
)

disp_win_trans
# Simple feature collection with 2 features and 0 fields
# geometry type:  POINT
# dimension:      XY
# bbox:           xmin: -112073.8 ymin: -552988 xmax: 770239.1 ymax: 1345785
# projected CRS:  USA_Contiguous_Albers_Equal_Area_Conic
# st_sfc.st_point.c..97.2..32.55....st_point.c..85.55..49.2....
# 1                                     POINT (-112073.8 -552988)
# 2                                      POINT (770239.1 1345785)