Generate sf objects (2)

dsf <- st_as_sf(d, coords = c("long", "lat"), crs = 4326)
dsf

## Simple feature collection with 4 features and 2 fields
## Geometry type: POINT
## Dimension:     XY
## Bounding box:  xmin: -3.703339 ymin: 40.41673 xmax: 12.49637 ymax: 51.50986
## Geodetic CRS:  WGS 84
## # A tibble: 4 × 3
##   place  value             geometry
## * <chr>  <dbl>          <POINT [°]>
## 1 London   200 (-0.118092 51.50986)
## 2 Paris    300  (2.349014 48.86472)
## 3 Madrid   400 (-3.703339 40.41673)
## 4 Rome     500  (12.49637 41.90278)