Add some basic docs

src/rostopics_to_timeseries/RosTopicFilteringScheme.py

@@ -2,6 +2,11 @@
 from rostopics_to_timeseries.Smoother import Smoother
 
 class RosTopicFilteringScheme(object):
+    """A class for configuring timeseries merging.
+    Args:
+        resampling_rate: sampling rate of timeseries.
+    """
+
     def __init__(self, resampling_rate):
         pass
         self.filters = []
@@ -10,6 +15,17 @@ def __init__(self, resampling_rate):
         self.rate = resampling_rate
 
     def add_filter(self, topic_name, msg_type, filter_class):
+        """Add a filter to fillter message from a specific topic.
+        Args:
+            topic_name: name of topic in string.
+
+            msg_type: type of message of the topic.
+
+            filter_class: class of message filer, has to be a subclass
+                of TopicMsgFilter.
+        """
+
+
         if not issubclass(filter_class, TopicMsgFilter):
             raise Exception("Filter class to be added is not a subclass of TopicMsgFilter.")
         self.filters.append(

src/rostopics_to_timeseries/RostopicsToTimeseries.py

@@ -16,7 +16,8 @@
 class RostopicsToTimeseries(object):
     """
     Args:
-        topic_filtering_config: [TODO]
+        topic_filtering_config: instance of RosTopicFilteringScheme
+            containing configuration of timeseries.
     """
 
     def __init__(self, topic_filtering_config):

src/rostopics_to_timeseries/TopicMsgFilter.py

@@ -3,18 +3,42 @@ def __init__(self):
         pass
 
     def convert(self, msg):
+        """function for filtering a message
+        Args:
+            msg: message to be filtered.
+        
+        Returns:
+            a list of numbers which is one frame of the timeseries
+        """
+
         raise Exception("Unimplemented")
 
     @staticmethod
     def vector_size():
+        """
+        Returns: number of dimensions of the timeseries.
+        """
+
         raise Exception("Unimplemented")
 
     @staticmethod
     def vector_meaning():
+        """
+        Returns: a list of string indicating the meaning of 
+            each dimension of the timeseries.
+        """
+
         raise Exception("Unimplemented")
 
     @staticmethod
     def get_time(msg):
+        """Extract time from a message
+        Args:
+            msg: the message whose time is to be extracted
+
+        Returns: an instance of <class 'genpy.rostime.Time'>
+        """
+
         return msg.header.stamp
 
 class BaxterEndpointStateFilter(TopicMsgFilter):