VegaFusion 1.3#
Transformed data for compound charts, Java library
By: Jon Mease
The VegaFusion team is happy to announce the release of version 1.3. Along with usual bug fixes and updates to the core Arrow and DataFusion dependencies, this release includes an enhancement to the transformed_data function to make it compatible with compound charts, adds DuckDB 0.8 support, and adds a new Java API.
Extract transformed data from compound Altair charts#
The VegaFusion transformed_data function can be used to extract the transformed data from an Altair chart object as a pandas DataFrame. Prior to 1.3.0, transformed_data was only supported on simple charts that involve only a single mark. Now, compound layered and concatenated charts are supported as well. In the case of a compound chart, transformed_data will return a list of pandas DataFrame’s rather than single DataFrame.
Example: Histogram with a Global Mean Overlay#
Here is an example based on the Histogram with a Global Mean Overlay example from the Altair gallery.
import altair as alt
import vegafusion as vf
from vega_datasets import data
vf.enable()
source = data.movies.url
base = alt.Chart(source)
bar = base.mark_bar().encode(
alt.X('IMDB_Rating:Q').bin().axis(None),
y='count()'
)
rule = base.mark_rule(color='red').encode(
x='mean(IMDB_Rating):Q',
size=alt.value(5)
)
chart = bar + rule
chart
Because chart is composed of two subcharts, the result of vf.transformed_data will be a list of two DataFrames.
[hist_df, rule_df] = vf.transformed_data(chart)
hist_df
| | bin_maxbins_10_IMDB_Rating | bin_maxbins_10_IMDB_Rating_end | __count |
|---:|-----------------------------:|---------------------------------:|----------:|
| 0 | 6 | 7 | 985 |
| 1 | 3 | 4 | 100 |
| 2 | 7 | 8 | 741 |
| 3 | 5 | 6 | 633 |
| 4 | 8 | 9 | 204 |
| 5 | 2 | 3 | 43 |
| 6 | 4 | 5 | 273 |
| 7 | 9 | 10 | 4 |
| 8 | 1 | 2 | 5 |
rule_df
| | mean_IMDB_Rating |
|---:|-------------------:|
| 0 | 6.28347 |
DuckDB 0.8 Support#
VegaFusion’s DuckDB integration has been updated to support DuckDB 0.8.0
Java API#
VegaFusion 1.3 may now be embedded in Java applications using the new io.vegafusion.vegafusion jar, which is published to Maven Central.
This was accomplished by wrapping the VegaFusion Rust API with a JNI interface using the jni-rs crate.
Updates to Arrow and DataFusion dependencies#
VegaFusion 1.3 updates the dependency on arrow-rs to version 39.0 and DataFusion to version 25.0.
Learn more#
Check out these resources to learn more: