does altair have a "play button" for sliders? - python-3.x

Question

x = np.arange(100)
t = np.arange(100)
y = [p**2 for p in x]
source = pd.DataFrame({
't':t,
'x': x,
'f(x)': y
})
slider = alt.binding_range(min=int(min(t)), max=int(max(t)), step=1)
select_t = alt.selection_single(name="year", fields=['t'],
bind=slider, init={'year': 50})
alt.Chart(source).mark_line(point=True).encode(
alt.X('x',scale=alt.Scale(domain=(0,100))),
alt.Y('f(x)',scale=alt.Scale(domain=(0,10000)))
).add_selection(select_year).transform_filter(select_t)
so I'm putting together a simple animated point, and I've got the slider running ok. But I'd like it to run automatically. Is that possible?

Answer 1

No, there is not currently any direct way to automate the slider or produce an animation in Altair. Animations have been discussed within Vega (the renderer that underlies Altair), but have not yet been added to the implementation.

Answer 2

Here's how to add a Play button to play the slider.
HTML('''
<button onclick="play()">Play</button>
<script>
var timer;
function play(){
// restart if max
slider = document.querySelector("input[type=range]")
if (slider.value==slider.max) {
slider.value = slider.min
slider.dispatchEvent(new Event("input"))
}
timer = setInterval(step, 200) // change speed here
}
function step(){
slider = document.querySelector("input[type=range]")
slider.stepUp() // use defult step
slider.dispatchEvent(new Event("input"))
if (slider.value==slider.max){
clearInterval(timer)
}
}
</script>
''')