Calmcode - polars: sort-filter

Sorting and filtering is certainly useful too.

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This is the code that we start with.

import polars as pl

# First "read" in the data.
df = pl.read_csv("wowah_data.csv", parse_dates=False)
df.columns = [c.replace(" ", "") for c in df.columns]
df = df.lazy()

def set_types(dataf):
    return (dataf.with_columns([
                pl.col("guild") != -1,
                pl.col("timestamp").str.strptime(pl.Datetime, fmt="%m/%d/%y %H:%M:%S"),
            ]))

# We can re-use this function in a pipeline.
df.pipe(set_types).collect()

Sorting via .sort

Polars can also sort the dataframe. Let's sort the dataset.

df.pipe(set_types).sort(["char", "timestamp"]).collect()

Create a subset with .filter

We can also limit our view by creating a subset. We can use the filter method for that.

(df
  .filter(pl.col("char") == 21)
  .pipe(set_types)
  .sort(["char", "timestamp"])
  .collect())