Joining sf object with data (4)

semi_join(x, y, by = "a")

## Simple feature collection with 1 feature and 1 field
## Geometry type: POINT
## Dimension:     XY
## Bounding box:  xmin: 1 ymin: 1 xmax: 1 ymax: 1
## CRS:           NA
##   a        geom
## 1 2 POINT (1 1)