Resolve empty vis bug for geographic data types

[micahtyong]

Overview

Previously, choropleth visualizations would not appear when x_attr or y_attr was abbreviated. With this change, all choropleth visualizations should appear as expected.

Changes

• Modifications in vislib/altair/Choropleth.py

Example Output

Now, when we run

import pandas as pd
import lux
df = pd.read_csv("https://raw.githubusercontent.com/lux-org/lux-datasets/master/data/hpi.csv")
df

we should get the following output with no empty visualizations.

[codecov]

Codecov Report

Merging #318 (c04b3a8) into master (f45d051) will decrease coverage by 0.11%.
The diff coverage is n/a.

❗ Current head c04b3a8 differs from pull request most recent head 7484b91. Consider uploading reports for the commit 7484b91 to get more accurate results

@@            Coverage Diff             @@
##           master     #318      +/-   ##
==========================================
- Coverage   80.98%   80.87%   -0.12%     
==========================================
  Files          50       50              
  Lines        3618     3618              
==========================================
- Hits         2930     2926       -4     
- Misses        688      692       +4     

Impacted Files	Coverage Δ
lux/vislib/altair/Choropleth.py	94.20% <ø> (ø)
lux/vislib/altair/Heatmap.py	93.10% <0.00%> (-3.45%)	⬇️
lux/vislib/altair/ScatterChart.py	93.93% <0.00%> (-3.04%)	⬇️
lux/vislib/matplotlib/Heatmap.py	96.66% <0.00%> (-1.67%)	⬇️
lux/vislib/matplotlib/ScatterChart.py	75.29% <0.00%> (-1.18%)	⬇️

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[dorisjlee]

This looks great, thanks @micahtyong!