I have a large dataframe -> lazyframe that was cut by the Expr.cut function. Now I would like to iterate through these categories, but I failed to find an effective way.
When I use group_by, it tells me it is not iterable (unless I collect it before the grouping). It raises:

TypeError: 'LazyGroupBy' object is not iterable

I really don’t want to filter the whole lazyframe for every category. How to achieve it?

The code I would love to be working (namely the for cycle in the end):

import polars as pl
import numpy as np

data = pl.LazyFrame(dict(
    a = np.linspace(1,5,100),
    b = np.linspace(20,30,100),
    ))


N_bins = 10
cutPoints = np.linspace(
    data.select(pl.max("a")).collect(),
    data.select(pl.min("a")).collect(),
    N_bins
    )

data = data.with_columns(
    pl.col("a").cut(cutPoints)
    )
groups = data.group_by("a")

for name, group in groups: 
    print( name)
    print(group)