## compare_draws()


Extract and stack draws from multiple groups (e.g., posterior and prior).


Usage


``` python
compare_draws(
    dt,
    *var_names,
    groups=None,
    group_name="source",
)
```


Calls [parameter_draws()](parameter_draws.md#tidydraws.parameter_draws) for each group, adds a column identifying the source group, and concatenates the results into a single DataFrame for easy comparison.


## Parameters


`dt: xr.DataTree or arviz.InferenceData`  
ArviZ InferenceData or xarray DataTree object.

`*var_names: str`  
Names of variables to extract (as for [parameter_draws()](parameter_draws.md#tidydraws.parameter_draws)).

`groups: list[str] | None = None`  
Which groups to extract and stack. Defaults to `["posterior", "prior"]` when `None`.

`group_name: str = ``"source"`  
Name of the column identifying the source group. Default "source".


## Returns


`pl.DataFrame`  
Stacked draws with an additional column (group_name) indicating source.


## Example

Extract posterior and prior for side-by-side forest plots

compare_df = compare_draws(dt, "beta", groups=\["posterior", "prior"\]) \# -\> columns: chain, draw, groups, beta, source \# -\> source in {"posterior", "prior"}