FabricDataFrames dynamically expose semantic functions based on logic defined by each function. For example, the is_holiday function shows up in the autocomplete suggestions when you're working on a FabricDataFrame containing both a datetime column and a country column.

Each semantic function uses information about the data types, metadata (such as Power BI data categories), and the data in a FabricDataFrame or FabricSeries to determine its relevance to the particular data on which you're working.

Semantic functions are automatically discovered when annotated with the @semantic_function decorator. You can think of semantic functions as being similar to C# extension methods applied to the popular DataFrame concept.

Usually a FabricDataFrame is retrieved using fabric.read_table(...) or fabric.evaluate_measure(...)

from sempy.fabric import FabricDataFrame

df = FabricDataFrame(
    {"country": ["US", "AT"],
        "lat": [40.7128, 47.8095],
        "long": [-74.0060, 13.0550]},
    column_metadata={"lat": {"data_category": "Latitude"}, "long": {"data_category": "Longitude"}},
)

# Convert to GeoPandas dataframe
df_geo = df.to_geopandas(lat_col="lat", long_col="long")

# Use the explore function to visualize the data
df_geo.explore()

You can also create ad-hoc semantic functions

from sempy.fabric import FabricDataFrame, FabricSeries
from sempy.fabric.matcher import CountryMatcher, CityMatcher
from sempy.functions import semantic_function, semantic_parameters

@semantic_function("is_capital")
@semantic_parameters(col_country=CountryMatcher, col_city=CityMatcher)
def _is_captial(df: FabricDataFrame, col_country: str, col_city: str) -> FabricSeries:
    """Returns true if the city is a capital of the country"""
    capitals = {
        "US": ["Washington"],
        "AT": ["Vienna"],
        # ...
    }

    return df[[col_country, col_city]] \
        .apply(lambda row: row[1] in capitals[row[0]], axis=1)

Create a conda environment with the following command:

conda env create -f environment.yml -n sempy-func
conda activate sempy-func

For each package (e.g. holidays), run

cd holidays
pip install -e .
pytest -s tests/

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