add Trains logger

docs/source/loggers.rst

@@ -10,6 +10,47 @@ These loggers may be more unstable, in development, or not fully tested yet.
 
 ---------
 
+allegro.ai TRAINS
+^^^^^^^^^^^^^^^^^
+
+`allegro.ai <https://github.com/allegroai/trains/>`_ is a third-party logger.
+To use :class:`~pl_bolts.loggers.TrainsLogger` as your logger do the following.
+First, install the package:
+
+.. code-block:: bash
+
+    pip install trains
+
+Then configure the logger and pass it to the :class:`~pl_bolts.trainer.trainer.Trainer`:
+
+.. testcode::
+
+    from pl_bolts.loggers import TrainsLogger
+    trains_logger = TrainsLogger(
+        project_name='examples',
+        task_name='pytorch lightning test',
+    )
+    trainer = Trainer(logger=trains_logger)
+
+.. testoutput::
+    :options: +ELLIPSIS, +NORMALIZE_WHITESPACE
+    :hide:
+
+    TRAINS Task: ...
+    TRAINS results page: ...
+
+.. testcode::
+
+    class MyModule(LightningModule):
+        def __init__(self):
+            some_img = fake_image()
+            self.logger.experiment.log_image('debug', 'generated_image_0', some_img, 0)
+
+.. seealso::
+    :class:`~pl_bolts.loggers.TrainsLogger` docs.
+
+---------
+
 Your Logger
 -----------
 Add your loggers here!

pl_bolts/loggers/__init__.py

@@ -1,3 +1,12 @@
 """
 Collection of PyTorchLightning loggers
 """
+
+__all__ = []
+
+try:
+    from pytorch_lightning.loggers.trains import TrainsLogger
+except ImportError:  # pragma: no-cover
+    pass  # pragma: no-cover
+else:
+    __all__.append('TrainsLogger')