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2025-09-07 22:09:54 +02:00
"""
Built-in datasets for demonstration, educational and test purposes.
"""
import os
from importlib import import_module
import narwhals.stable.v1 as nw
AVAILABLE_BACKENDS = {"pandas", "polars", "pyarrow", "modin", "cudf"}
BACKENDS_WITH_INDEX_SUPPORT = {"pandas", "modin", "cudf"}
def gapminder(
datetimes=False,
centroids=False,
year=None,
pretty_names=False,
return_type="pandas",
):
"""
Each row represents a country on a given year.
https://www.gapminder.org/data/
Parameters
----------
datetimes: bool
Whether or not 'year' column will converted to datetime type
centroids: bool
If True, ['centroid_lat', 'centroid_lon'] columns are added
year: int | None
If provided, the dataset will be filtered for that year
pretty_names: bool
If True, prettifies the column names
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
Dataframe with 1704 rows and the following columns:
`['country', 'continent', 'year', 'lifeExp', 'pop', 'gdpPercap',
'iso_alpha', 'iso_num']`.
If `datetimes` is True, the 'year' column will be a datetime column
If `centroids` is True, two new columns are added: ['centroid_lat', 'centroid_lon']
If `year` is an integer, the dataset will be filtered for that year
"""
df = nw.from_native(
_get_dataset("gapminder", return_type=return_type), eager_only=True
)
if year:
df = df.filter(nw.col("year") == year)
if datetimes:
df = df.with_columns(
# Concatenate the year value with the literal "-01-01" so that it can be
# casted to datetime from "%Y-%m-%d" format
nw.concat_str(
[nw.col("year").cast(nw.String()), nw.lit("-01-01")]
).str.to_datetime(format="%Y-%m-%d")
)
if not centroids:
df = df.drop("centroid_lat", "centroid_lon")
if pretty_names:
df = df.rename(
dict(
country="Country",
continent="Continent",
year="Year",
lifeExp="Life Expectancy",
gdpPercap="GDP per Capita",
pop="Population",
iso_alpha="ISO Alpha Country Code",
iso_num="ISO Numeric Country Code",
centroid_lat="Centroid Latitude",
centroid_lon="Centroid Longitude",
)
)
return df.to_native()
def tips(pretty_names=False, return_type="pandas"):
"""
Each row represents a restaurant bill.
https://vincentarelbundock.github.io/Rdatasets/doc/reshape2/tips.html
Parameters
----------
pretty_names: bool
If True, prettifies the column names
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
Dataframe with 244 rows and the following columns:
`['total_bill', 'tip', 'sex', 'smoker', 'day', 'time', 'size']`.
"""
df = nw.from_native(_get_dataset("tips", return_type=return_type), eager_only=True)
if pretty_names:
df = df.rename(
dict(
total_bill="Total Bill",
tip="Tip",
sex="Payer Gender",
smoker="Smokers at Table",
day="Day of Week",
time="Meal",
size="Party Size",
)
)
return df.to_native()
def iris(return_type="pandas"):
"""
Each row represents a flower.
https://en.wikipedia.org/wiki/Iris_flower_data_set
Parameters
----------
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
Dataframe with 150 rows and the following columns:
`['sepal_length', 'sepal_width', 'petal_length', 'petal_width', 'species', 'species_id']`.
"""
return _get_dataset("iris", return_type=return_type)
def wind(return_type="pandas"):
"""
Each row represents a level of wind intensity in a cardinal direction, and its frequency.
Parameters
----------
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
Dataframe with 128 rows and the following columns:
`['direction', 'strength', 'frequency']`.
"""
return _get_dataset("wind", return_type=return_type)
def election(return_type="pandas"):
"""
Each row represents voting results for an electoral district in the 2013 Montreal
mayoral election.
Parameters
----------
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
Dataframe with 58 rows and the following columns:
`['district', 'Coderre', 'Bergeron', 'Joly', 'total', 'winner', 'result', 'district_id']`.
"""
return _get_dataset("election", return_type=return_type)
def election_geojson():
"""
Each feature represents an electoral district in the 2013 Montreal mayoral election.
Returns
-------
A GeoJSON-formatted `dict` with 58 polygon or multi-polygon features whose `id`
is an electoral district numerical ID and whose `district` property is the ID and
district name.
"""
import gzip
import json
import os
path = os.path.join(
os.path.dirname(os.path.dirname(__file__)),
"package_data",
"datasets",
"election.geojson.gz",
)
with gzip.GzipFile(path, "r") as f:
result = json.loads(f.read().decode("utf-8"))
return result
def carshare(return_type="pandas"):
"""
Each row represents the availability of car-sharing services near the centroid of a zone
in Montreal over a month-long period.
Parameters
----------
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
Dataframe` with 249 rows and the following columns:
`['centroid_lat', 'centroid_lon', 'car_hours', 'peak_hour']`.
"""
return _get_dataset("carshare", return_type=return_type)
def stocks(indexed=False, datetimes=False, return_type="pandas"):
"""
Each row in this wide dataset represents closing prices from 6 tech stocks in 2018/2019.
Parameters
----------
indexed: bool
Whether or not the 'date' column is used as the index and the column index
is named 'company'. Applicable only if `return_type='pandas'`
datetimes: bool
Whether or not the 'date' column will be of datetime type
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
Dataframe with 100 rows and the following columns:
`['date', 'GOOG', 'AAPL', 'AMZN', 'FB', 'NFLX', 'MSFT']`.
If `indexed` is True, the 'date' column is used as the index and the column index
is named 'company'
If `datetimes` is True, the 'date' column will be a datetime column
"""
if indexed and return_type not in BACKENDS_WITH_INDEX_SUPPORT:
msg = f"Backend '{return_type}' does not support setting index"
raise NotImplementedError(msg)
df = nw.from_native(
_get_dataset("stocks", return_type=return_type), eager_only=True
).with_columns(nw.col("date").cast(nw.String()))
if datetimes:
df = df.with_columns(nw.col("date").str.to_datetime())
if indexed: # then it must be pandas
df = df.to_native().set_index("date")
df.columns.name = "company"
return df
return df.to_native()
def experiment(indexed=False, return_type="pandas"):
"""
Each row in this wide dataset represents the results of 100 simulated participants
on three hypothetical experiments, along with their gender and control/treatment group.
Parameters
----------
indexed: bool
If True, then the index is named "participant".
Applicable only if `return_type='pandas'`
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
Dataframe with 100 rows and the following columns:
`['experiment_1', 'experiment_2', 'experiment_3', 'gender', 'group']`.
If `indexed` is True, the data frame index is named "participant"
"""
if indexed and return_type not in BACKENDS_WITH_INDEX_SUPPORT:
msg = f"Backend '{return_type}' does not support setting index"
raise NotImplementedError(msg)
df = nw.from_native(
_get_dataset("experiment", return_type=return_type), eager_only=True
)
if indexed: # then it must be pandas
df = df.to_native()
df.index.name = "participant"
return df
return df.to_native()
def medals_wide(indexed=False, return_type="pandas"):
"""
This dataset represents the medal table for Olympic Short Track Speed Skating for the
top three nations as of 2020.
Parameters
----------
indexed: bool
Whether or not the 'nation' column is used as the index and the column index
is named 'medal'. Applicable only if `return_type='pandas'`
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
Dataframe with 3 rows and the following columns:
`['nation', 'gold', 'silver', 'bronze']`.
If `indexed` is True, the 'nation' column is used as the index and the column index
is named 'medal'
"""
if indexed and return_type not in BACKENDS_WITH_INDEX_SUPPORT:
msg = f"Backend '{return_type}' does not support setting index"
raise NotImplementedError(msg)
df = nw.from_native(
_get_dataset("medals", return_type=return_type), eager_only=True
)
if indexed: # then it must be pandas
df = df.to_native().set_index("nation")
df.columns.name = "medal"
return df
return df.to_native()
def medals_long(indexed=False, return_type="pandas"):
"""
This dataset represents the medal table for Olympic Short Track Speed Skating for the
top three nations as of 2020.
Parameters
----------
indexed: bool
Whether or not the 'nation' column is used as the index.
Applicable only if `return_type='pandas'`
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
Dataframe with 9 rows and the following columns: `['nation', 'medal', 'count']`.
If `indexed` is True, the 'nation' column is used as the index.
"""
if indexed and return_type not in BACKENDS_WITH_INDEX_SUPPORT:
msg = f"Backend '{return_type}' does not support setting index"
raise NotImplementedError(msg)
df = nw.from_native(
_get_dataset("medals", return_type=return_type), eager_only=True
).unpivot(
index=["nation"],
value_name="count",
variable_name="medal",
)
if indexed:
df = nw.maybe_set_index(df, "nation")
return df.to_native()
def _get_dataset(d, return_type):
"""
Loads the dataset using the specified backend.
Notice that the available backends are 'pandas', 'polars', 'pyarrow' and they all have
a `read_csv` function (pyarrow has it via pyarrow.csv). Therefore we can dynamically
load the library using `importlib.import_module` and then call
`backend.read_csv(filepath)`.
Parameters
----------
d: str
Name of the dataset to load.
return_type: {'pandas', 'polars', 'pyarrow', 'modin', 'cudf'}
Type of the resulting dataframe
Returns
-------
Dataframe of `return_type` type
"""
filepath = os.path.join(
os.path.dirname(os.path.dirname(__file__)),
"package_data",
"datasets",
d + ".csv.gz",
)
if return_type not in AVAILABLE_BACKENDS:
msg = (
f"Unsupported return_type. Found {return_type}, expected one "
f"of {AVAILABLE_BACKENDS}"
)
raise NotImplementedError(msg)
try:
if return_type == "pyarrow":
module_to_load = "pyarrow.csv"
elif return_type == "modin":
module_to_load = "modin.pandas"
else:
module_to_load = return_type
backend = import_module(module_to_load)
except ModuleNotFoundError:
msg = f"return_type={return_type}, but {return_type} is not installed"
raise ModuleNotFoundError(msg)
try:
return backend.read_csv(filepath)
except Exception as e:
msg = f"Unable to read '{d}' dataset due to: {e}"
raise Exception(msg).with_traceback(e.__traceback__)