Plot.plot({
x: {domain : [0,3.5], ticks: 4, tickFormat: s => s.toFixed(0)},
y: {domain : [0,1], ticks : 1},
marks: [
Plot.ruleY([0]),
Plot.ruleX(practice_data2, { x: "this", y: "that", tip: true }),
Plot.dot(practice_data2, { x: "this", y: y => y.that > 0 ? y.that + .01 : y.that, tip: true })
]
})