def extract_data(chart: alt.Chart) -> pd.DataFrame:
"""Extract transformed data from a chart.
This only works with data and transform defined at the
top level of the chart.
Parameters
----------
chart : alt.Chart
The chart instance from which the data and transform
will be extracted
Returns
-------
df_transformed : pd.DataFrame
The extracted and transformed dataframe.
"""
return apply(to_dataframe(chart.data, chart), chart.transform)
def extract_data(
chart: alt.Chart, apply_encoding_transforms: bool = True
) -> pd.DataFrame:
"""Extract transformed data from a chart.
This only works with data and transform defined at the
top level of the chart.
Parameters
----------
chart : alt.Chart
The chart instance from which the data and transform
will be extracted
apply_encoding_transforms : bool
If True (default), then apply transforms specified within an
encoding as well as those specified directly in the transforms
attribute.
Returns
-------
df_transformed : pd.DataFrame
The extracted and transformed dataframe.
Example
-------
>>> import pandas as pd
>>> data = pd.DataFrame({'x': range(5), 'y': list('ABCAB')})
>>> chart = alt.Chart(data).mark_bar().encode(x='sum(x)', y='y')
>>> extract_data(chart)
y sum_x
0 A 3
1 B 5
2 C 2
"""
if apply_encoding_transforms:
chart = extract_transform(chart)
return apply(to_dataframe(chart.data, chart), chart.transform)
def test_named_to_dataframe(df, chart, named_data, data_type):
data = data_type(named_data)
assert df.equals(to_dataframe(data, context=chart))
def test_inline_to_dataframe(df, inline_data, data_type):
data = data_type(inline_data)
assert df.equals(to_dataframe(data))
def test_json_to_dataframe(df, json_data, data_type):
data = data_type(json_data)
assert df.equals(to_dataframe(data))
def test_csv_to_dataframe(df, csv_data, data_type):
data = data_type(csv_data)
assert df.equals(to_dataframe(data))
def test_sequence_to_dataframe(df, sequence_data, data_type):
data = data_type(sequence_data)
assert df[["x"]].equals(to_dataframe(data))