Recreating The PyLDAvis Chart In Altair - Filtered Data With Empty Selection

I am trying to recreating the classic pyLDAvis visualization for topic modelling in Altair. I've hit a snag when it comes to filtering. In the pyLDAvis chart, an empty selection in

Solution 1:

You could overlay a separate bar plot on top of the first one and only use transform filter on this overlaid plot. To not show any segments on the start you can set the empty behavior of the selection.

import altair as alt
import pandas as pd


# I modified these values slightly
data={
 'Term': ['algorithm','learning','learning','algorithm','algorithm','learning'],
 'Freq_x': [1330,1153,504.42,296.69,177.59,140.35],
 'Total': [1330, 1353,1353.7,1330.47,1330.47,1353.7],
 'Category': ['Default', 'Default', 'Topic1', 'Topic1', 'Topic2', 'Topic2'],
 'logprob': [30.0, 27.0, -5.116, -5.1418, -5.4112, -5.5271],
 'loglift': [30.0, 27.0, 0.0975, 0.0891, -0.1803, -0.3135],
 'saliency_ind': [0, 3, 76, 77, 181, 186],
 'x': [None,None,-0.0080,-0.0080,-0.0053,-0.0053],
 'y': [None,None,-0.0056,-0.0056, 0.0003,0.0003],
 'topics': [None,None, 1.0, 1.0, 2.0, 2.0],
 'cluster': [None,None, 1.0, 1.0, 1.0, 1.0],
 'Freq_y': [None,None,20.39,20.39,14.18,14.18]}

df=pd.DataFrame(data)

pts = alt.selection(type="single", fields=['Category'], empty='none')

points=alt.Chart().mark_circle(tooltip=True).encode(
    x='mean(x)',
    y='mean(y)',
    size='Freq_y',
    tooltip=['topics', 'cluster'],
    detail='Category',
    color=alt.condition(pts, alt.value('#F28E2B'), alt.value('#4E79A7'))
).add_selection(pts)

bars=alt.Chart().mark_bar().encode(
    x='Freq_x',
    y=alt.Y('Term', sort='-x'),
    tooltip=['Total'],
)

bars2=alt.Chart().mark_bar(color='#F28E2B').encode(
    x='Freq_x',
    y=alt.Y('Term', sort='-x'),
    tooltip=['Freq_x'],
).transform_filter(
    pts
)

alt.hconcat(points,bars+bars2, data=df).resolve_legend(
    color="independent",
    size="independent"
)

I believe this solves both the issues you mentioned. There is a third one, which is that the bars don't resort dynamically as in your example, but I am not sure how to solve that.