.interactive only working with certain data types.

[Alcampopiano]

Hi Altair users,

Is there a reason why adding ".interactive" does not work for the following example? I'm unable to pan or zoom. However if I use a temporal data type for the dates, then it works (although the rect marks now go on forever in the past).

df=pd.DataFrame({'days_between': ['2017-01-01', '2017-01-02', '2017-01-03'], 'variable': ['person_1', 'person_2', 'person_3'], 'value': [1,2,3]})

alt.Chart(df).mark_rect().encode(
    x='days_between:O',
    y='variable:N',
    color=alt.Color('value:Q', scale=alt.Scale(range=['green','yellow','red']))).properties(width=300, height=100).interactive()

With a temporal data type:

...
 x='days_between:T',
...

Any help is appreciated.

Al

[Casyfill]

same issue - .interactive() does not work with geoshapes for me:

alt.Chart(boundaries).project(type="mercator",center=[-73.99,40.72]
).properties(width=500,height=300).mark_geoshape(fill='lightgrey').encode().interactive()

results in

Javascript Error: Expression parse error: " ? {unit: \"\", intervals: []} : null". This usually means there's a typo in your chart specification. See the JavaScript console for the full traceback.

[Alcampopiano]

@Casyfill I don't think this is the same issue as mine since I am not getting an error.

[jakevdp]

This is a known issue; see #679 and vega/vega-lite#3306

[Alcampopiano]

Jake, since my issue is not related to geo, should it be closed?

[jakevdp]

Sorry, I thought it was related to geo.

Reading more closely, it looks like your issue is that interactive() does not work on ordinal/nominal scales, is that right? If so, that's by design, so perhaps it just needs to be better documented?

[Alcampopiano]

Yes, that was the issue. Thanks for clarifying.

[JarnoRFB]

Would there be any way to make this work? As I can see vega-lite achieves pan and zoom by a grid selection https://vega.github.io/vega-lite/examples/selection_translate_scatterplot_drag.html. Is this only applicable to quantitative variables? I am trying to make a correlation matrix with many variables and being able to zoom in would be very helpful.

[jakevdp]

Vega-Lite achieves pan/zoom behavior by binding an interval selection to "scales". This is precisely what calling chart.interactive() does in Altair.

The issue here is that interval selections bound to scales for non-quantitative encodings do not have any effect in Vega-lite, and from the linked issues this appears to be by design. So no, there currently is no way to make this work.