Translating as `pandas.Categories`

[rsundqvist]

The function below works but is limited.

import pandas as pd
from id_translation.offline import TranslationMap

def translate_as_categories(df: pd.DataFrame, tmap: TranslationMap) -> pd.DataFrame:
    from id_translation.dio import resolve_io

    dtypes = {
        # sort_index() to ensure ordering by ID
        column: pd.CategoricalDtype(pd.Series(tmap[column]).sort_index(), ordered=True) 
        for column in df
    }
    return resolve_io(df).insert(df, names=list(df), tmap=tmap, copy=False).astype(dtypes)

Not very convenient though, and requires some knowledge of internal id_translation types.

1. Setup

   >>> data = {1999: "Sofia", 1991: "Richard"}
   
   >>> from id_translation import Translator
   >>> translator = Translator({"people":  data})
   >>> translator
   Translator(online=False: cache=TranslationMap('people': 2 IDs))

2. Create data

   >>> df = pd.Series(list(data)).to_frame("people")
   >>> df = df.sample(4, replace=True).reset_index(drop=True)
   >>> df.T
   people  1999  1999  1991  1999

3. Apply

   
   >>> df = translate_as_categories(df, translator.cache)

4. Result

   >>> df.T
   people  1999:Sofia  1999:Sofia  1991:Richard  1999:Sofia
   
   >>> df["people"].dtype
   CategoricalDtype(categories=['1991:Richard', '1999:Sofia'], ordered=True, categories_dtype=object)

Maybe it's enough to put up at documentation/examples.

[rsundqvist]

Issues with naïve solution

• Failed translations will show up as "real" categories
• Must be offline, or fetch twice