[ python ] heatmap with altair & polars

import polars as pl
import altair as alt

# make DataFrame

---

df = pl.DataFrame( { 
    'a' : [ 1, 3 ,4 ], 
    'b' : [ 1, 3, 4 ],
    'c' : [ 3, 8, 4 ]
} )

# check corr

---

df_c = df.corr().with_columns(
    pl.Series( df.columns ).alias( 'col' )
).unpivot( index = 'col' )

# Visualiztion with altair