julia> using RDatasets

julia> iris = dataset("datasets", "iris")

julia> iris[iris[:Species] .== "setosa", :]
50x5 DataFrame
|-------|-------------|------------|-------------|------------|----------|
| Row # | SepalLength | SepalWidth | PetalLength | PetalWidth | Species |
| 1 | 5.1 | 3.5 | 1.4 | 0.2 | "setosa" |
| 2 | 4.9 | 3.0 | 1.4 | 0.2 | "setosa" |
| 3 | 4.7 | 3.2 | 1.3 | 0.2 | "setosa" |
| 4 | 4.6 | 3.1 | 1.5 | 0.2 | "setosa" |
| 5 | 5.0 | 3.6 | 1.4 | 0.2 | "setosa" |
| 6 | 5.4 | 3.9 | 1.7 | 0.4 | "setosa" |
| 7 | 4.6 | 3.4 | 1.4 | 0.3 | "setosa" |
| 8 | 5.0 | 3.4 | 1.5 | 0.2 | "setosa" |
| 9 | 4.4 | 2.9 | 1.4 | 0.2 | "setosa" |