Added functionality to give a description in the progress bar (#401)

* Update pbar.py

* Update ensemble.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update ensemble.py

* Update pbar.py

* Update ensemble.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/emcee/ensemble.py

@@ -261,6 +261,7 @@ def sample(
         thin=None,
         store=True,
         progress=False,
+        progress_kwargs=None,
     ):
         """Advance the chain as a generator
 
@@ -287,6 +288,8 @@ def sample(
                 ``'notebook'``, which shows a progress bar suitable for
                 Jupyter notebooks.  If ``False``, no progress bar will be
                 shown.
+            progress_kwargs (Optional[dict]): A ``dict`` of keyword arguments
+                to be passed to the tqdm call.
             skip_initial_state_check (Optional[bool]): If ``True``, a check
                 that the initial_state can fully explore the space will be
                 skipped. (default: ``False``)
@@ -383,10 +386,12 @@ def sample(
         model = Model(
             self.log_prob_fn, self.compute_log_prob, map_fn, self._random
         )
+        if progress_kwargs is None:
+            progress_kwargs = {}
 
         # Inject the progress bar
         total = None if iterations is None else iterations * yield_step
-        with get_progress_bar(progress, total) as pbar:
+        with get_progress_bar(progress, total, **progress_kwargs) as pbar:
             i = 0
             for _ in count() if iterations is None else range(iterations):
                 for _ in range(yield_step):

src/emcee/pbar.py

@@ -28,7 +28,7 @@ def update(self, count):
         pass
 
 
-def get_progress_bar(display, total):
+def get_progress_bar(display, total, **kwargs):
     """Get a progress bar interface with given properties
 
     If the tqdm library is not installed, this will always return a "progress
@@ -38,6 +38,7 @@ def get_progress_bar(display, total):
         display (bool or str): Should the bar actually show the progress? Or a
                                string to indicate which tqdm bar to use.
         total (int): The total size of the progress bar.
+        kwargs (dict): Optional keyword arguments to be passed to the tqdm call.
 
     """
     if display:
@@ -49,8 +50,8 @@ def get_progress_bar(display, total):
             return _NoOpPBar()
         else:
             if display is True:
-                return tqdm.tqdm(total=total)
+                return tqdm.tqdm(total=total, **kwargs)
             else:
-                return getattr(tqdm, "tqdm_" + display)(total=total)
+                return getattr(tqdm, "tqdm_" + display)(total=total, **kwargs)
 
     return _NoOpPBar()