|
| 1 | +# /// script |
| 2 | +# requires-python = ">=3.11" |
| 3 | +# dependencies = [ |
| 4 | +# "duckdb==1.3.0", |
| 5 | +# "marimo", |
| 6 | +# "narwhals==1.40.0", |
| 7 | +# "pandas==2.2.3", |
| 8 | +# "polars==1.30.0", |
| 9 | +# "pyarrow==20.0.0", |
| 10 | +# ] |
| 11 | +# /// |
| 12 | + |
| 13 | +import marimo |
| 14 | + |
| 15 | +__generated_with = "0.13.7" |
| 16 | +app = marimo.App(width="medium") |
| 17 | + |
| 18 | + |
| 19 | +@app.cell |
| 20 | +def _(): |
| 21 | + import marimo as mo |
| 22 | + return (mo,) |
| 23 | + |
| 24 | + |
| 25 | +@app.cell(hide_code=True) |
| 26 | +def _(mo): |
| 27 | + mo.md(r"""# Eager vs Lazy DataFrames: One Fix to Make Your Code Work Anywhere""") |
| 28 | + return |
| 29 | + |
| 30 | + |
| 31 | +@app.cell |
| 32 | +def _(mo): |
| 33 | + mo.md(r"""## Motivation""") |
| 34 | + return |
| 35 | + |
| 36 | + |
| 37 | +@app.cell |
| 38 | +def _(): |
| 39 | + from datetime import datetime |
| 40 | + |
| 41 | + import pandas as pd |
| 42 | + import polars as pl |
| 43 | + |
| 44 | + data1 = {"store": [1, 1, 2], "date_id": [4, 5, 6]} |
| 45 | + data2 = {"store": [1, 2], "sales": [7, 8]} |
| 46 | + |
| 47 | + pandas_df1 = pd.DataFrame(data1) |
| 48 | + pandas_df2 = pd.DataFrame(data2) |
| 49 | + |
| 50 | + # The outputs are the same |
| 51 | + for _ in range(5): |
| 52 | + # Left join |
| 53 | + pandas_df = pd.merge(pandas_df1, pandas_df2, on="store", how="left") |
| 54 | + |
| 55 | + # Cumulative sum of sales within each store |
| 56 | + pandas_df["cumulative_sales"] = pandas_df.groupby("store")["sales"].cumsum() |
| 57 | + |
| 58 | + print(pandas_df) |
| 59 | + return data1, data2, datetime, pd, pl |
| 60 | + |
| 61 | + |
| 62 | +@app.cell |
| 63 | +def _(data1, data2, pl): |
| 64 | + polars_df1 = pl.DataFrame(data1).lazy() |
| 65 | + polars_df2 = pl.DataFrame(data2).lazy() |
| 66 | + |
| 67 | + # The outputs are not the same |
| 68 | + for _ in range(5): |
| 69 | + print( |
| 70 | + polars_df1.join(polars_df2, on="store", how="left") |
| 71 | + .with_columns(cumulative_sales=pl.col("sales").cum_sum().over("store")) |
| 72 | + .collect(engine="streaming") |
| 73 | + ) |
| 74 | + return |
| 75 | + |
| 76 | + |
| 77 | +@app.cell(hide_code=True) |
| 78 | +def _(mo): |
| 79 | + mo.md(r"""## Eager-only solution""") |
| 80 | + return |
| 81 | + |
| 82 | + |
| 83 | +@app.cell |
| 84 | +def _(datetime, pd): |
| 85 | + data = { |
| 86 | + "sale_date": [ |
| 87 | + datetime(2025, 5, 22), |
| 88 | + datetime(2025, 5, 23), |
| 89 | + datetime(2025, 5, 24), |
| 90 | + datetime(2025, 5, 22), |
| 91 | + datetime(2025, 5, 23), |
| 92 | + datetime(2025, 5, 24), |
| 93 | + ], |
| 94 | + "store": [ |
| 95 | + "Thimphu", |
| 96 | + "Thimphu", |
| 97 | + "Thimphu", |
| 98 | + "Paro", |
| 99 | + "Paro", |
| 100 | + "Paro", |
| 101 | + ], |
| 102 | + "sales": [1100, None, 1450, 501, 500, None], |
| 103 | + } |
| 104 | + |
| 105 | + pdf = pd.DataFrame(data) |
| 106 | + print(pdf) |
| 107 | + return (data,) |
| 108 | + |
| 109 | + |
| 110 | +@app.cell |
| 111 | +def _(): |
| 112 | + import narwhals as nw |
| 113 | + from narwhals.typing import IntoFrameT |
| 114 | + |
| 115 | + |
| 116 | + def agnostic_ffill_by_store(df_native: IntoFrameT) -> IntoFrameT: |
| 117 | + # Supports pandas and Polars.DataFrame, but not lazy ones. |
| 118 | + return ( |
| 119 | + nw.from_native(df_native) |
| 120 | + .with_columns( |
| 121 | + nw.col("sales").fill_null(strategy="forward").over("store") |
| 122 | + ) |
| 123 | + .to_native() |
| 124 | + ) |
| 125 | + return IntoFrameT, agnostic_ffill_by_store, nw |
| 126 | + |
| 127 | + |
| 128 | +@app.cell |
| 129 | +def _(agnostic_ffill_by_store, data, pd): |
| 130 | + # pandas.DataFrame |
| 131 | + df_pandas = pd.DataFrame(data) |
| 132 | + agnostic_ffill_by_store(df_pandas) |
| 133 | + return (df_pandas,) |
| 134 | + |
| 135 | + |
| 136 | +@app.cell |
| 137 | +def _(agnostic_ffill_by_store, data, pl): |
| 138 | + # polars.DataFrame |
| 139 | + df_polars = pl.DataFrame(data) |
| 140 | + agnostic_ffill_by_store(df_polars) |
| 141 | + return (df_polars,) |
| 142 | + |
| 143 | + |
| 144 | +@app.cell |
| 145 | +def _(): |
| 146 | + import duckdb |
| 147 | + |
| 148 | + duckdb_rel = duckdb.table("df_polars") |
| 149 | + duckdb_rel |
| 150 | + return (duckdb_rel,) |
| 151 | + |
| 152 | + |
| 153 | +@app.cell |
| 154 | +def _(): |
| 155 | + # agnostic_ffill_by_store(duckdb_rel) |
| 156 | + # Error: narwhals.exceptions.OrderDependentExprError: Order-dependent expressions are not supported for use in LazyFrame. |
| 157 | + return |
| 158 | + |
| 159 | + |
| 160 | +@app.cell(hide_code=True) |
| 161 | +def _(mo): |
| 162 | + mo.md(r"""## Eager and lazy solution""") |
| 163 | + return |
| 164 | + |
| 165 | + |
| 166 | +@app.cell |
| 167 | +def _(IntoFrameT, nw): |
| 168 | + def agnostic_ffill_by_store_improved(df_native: IntoFrameT) -> IntoFrameT: |
| 169 | + return ( |
| 170 | + nw.from_native(df_native) |
| 171 | + .with_columns( |
| 172 | + nw.col("sales") |
| 173 | + .fill_null(strategy="forward") |
| 174 | + # Note the `order_by` statement |
| 175 | + .over("store", order_by="sale_date") |
| 176 | + ) |
| 177 | + .to_native() |
| 178 | + ) |
| 179 | + return (agnostic_ffill_by_store_improved,) |
| 180 | + |
| 181 | + |
| 182 | +@app.cell |
| 183 | +def _(agnostic_ffill_by_store_improved, duckdb_rel): |
| 184 | + agnostic_ffill_by_store_improved(duckdb_rel) |
| 185 | + return |
| 186 | + |
| 187 | + |
| 188 | +@app.cell |
| 189 | +def _(agnostic_ffill_by_store_improved, df_polars): |
| 190 | + agnostic_ffill_by_store_improved(df_polars.lazy()).collect() |
| 191 | + return |
| 192 | + |
| 193 | + |
| 194 | +@app.cell |
| 195 | +def _(agnostic_ffill_by_store_improved, df_pandas): |
| 196 | + # Note that it still supports pandas |
| 197 | + print(agnostic_ffill_by_store_improved(df_pandas)) |
| 198 | + return |
| 199 | + |
| 200 | + |
| 201 | +@app.cell |
| 202 | +def _(): |
| 203 | + return |
| 204 | + |
| 205 | + |
| 206 | +if __name__ == "__main__": |
| 207 | + app.run() |
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