gistfile1.txt

from datetime import timedelta, datetime

import polars as pl

# Make a dataframe with a one hour time series at 10-min intervals for group "a"
df = (
  pl.DataFrame(
  {'date':pl.date_range(start,stop,timedelta(minutes=10))
  })
  .with_column(
    pl.lit('a').alias('group_id'))
   # Add a row count column for some simple values
  .with_row_count('value')
  # Remove the value at 20 minutes past the hour
  .filter(pl.col('value')!=2)
  )
 # Concatenate this dataframe with itself to form a separate group "b"
df2 = (
 pl.concat(
    [
    df,
    df.select(['value','date']).with_column(pl.lit('b').alias('group_id'))
    ]
 )
 )
dfList = []
for sub_df in df2.groupby("group_id"):
    dfList.append(
    sub_df.upsample('date','10m').interpolate().fill_null(strategy='forward')
    )
correctedDf = pl.concat(dfList)