Included additional links.

example_2.md

@@ -44,7 +44,7 @@ First, open a terminal and run the stretch driver launch file.
 roslaunch stretch_core stretch_driver.launch
 ```
 
-Then in a new terminal run the rplidar launch file from `stretch_core`.
+Then in a new terminal run the `rplidar.launch` file from `stretch_core`.
 ```bash
 # Terminal 2
 roslaunch stretch_core rplidar.launch
@@ -82,7 +82,7 @@ from sensor_msgs.msg import LaserScan
 class ScanFilter:
   """
   A class that implements a LaserScan filter that removes all of the points
-  that are not infront of the robot.
+  that are not in front of the robot.
   """
 	def __init__(self):
 		self.width = 1.0
@@ -93,11 +93,11 @@ class ScanFilter:
 
 	def callback(self,msg):
     """
-		Callback function to deal with incoming laserscan messages.
+		Callback function to deal with incoming LaserScan messages.
 		:param self: The self reference.
-		:param msg: The subscribed laserscan message.
+		:param msg: The subscribed LaserScan message.
 
-		:publishes msg: updated laserscan message.
+		:publishes msg: updated LaserScan message.
 		"""
 		angles = linspace(msg.angle_min, msg.angle_max, len(msg.ranges))
 		points = [r * sin(theta) if (theta < -2.5 or theta > 2.5) else inf for r,theta in zip(msg.ranges, angles)]
@@ -127,7 +127,7 @@ from numpy import linspace, inf
 from math import sin
 from sensor_msgs.msg import LaserScan
 ```
-You need to import rospy if you are writing a ROS Node. There are functions from numpy and math that are required within this code, thus why linspace, inf, and sin are imported. The `sensor_msgs.msg` import is so that we can subscribe and publish LaserScan messages.
+You need to import `rospy` if you are writing a ROS [Node](http://wiki.ros.org/Nodes). There are functions from `numpy` and `math` that are required within this code, thus why linspace, inf, and sin are imported. The `sensor_msgs.msg` import is so that we can subscribe and publish `LaserScan` messages.
 
 ```python
 self.width = 1
@@ -138,12 +138,12 @@ We're going to assume that the robot is pointing up the x-axis, so that any poin
 ```python
 self.sub = rospy.Subscriber('/scan', LaserScan, self.callback)
 ```
-Set up a subscriber.  We're going to subscribe to the topic *scan*, looking for LaserScan messages.  When a message comes in, ROS is going to pass it to the function "callback" automatically.
+Set up a subscriber.  We're going to subscribe to the topic *scan*, looking for `LaserScan` messages.  When a message comes in, ROS is going to pass it to the function "callback" automatically.
 
 ```python
 self.pub = rospy.Publisher('filtered_scan', LaserScan, queue_size=10)
 ```
-`pub = rospy.Publisher("filtered_scan", LaserScan, queue_size=10)` declares that your node is publishing to the *filtered_scan* topic using the message type LaserScan. This lets the master tell any nodes listening on *filtered_scan* that we are going to publish data on that topic.
+`pub = rospy.Publisher("filtered_scan", LaserScan, queue_size=10)` declares that your node is publishing to the *filtered_scan* topic using the message type `LaserScan`. This lets the master tell any nodes listening on *filtered_scan* that we are going to publish data on that topic.
 
 ```python
 angles = linspace(msg.angle_min, msg.angle_max, len(msg.ranges))
@@ -171,7 +171,7 @@ Substitute in the new ranges in the original message, and republish it.
 rospy.init_node('scan_filter')
 ScanFilter()
 ```
-The next line, `rospy.init_node(NAME, ...)`, is very important as it tells rospy the name of your node -- until rospy has this information, it cannot start communicating with the ROS Master. In this case, your node will take on the name talker. NOTE: the name must be a base name, i.e. it cannot contain any slashes "/".
+The next line, `rospy.init_node(NAME, ...)`, is very important as it tells rospy the name of your node -- until rospy has this information, it cannot start communicating with the ROS Master. **NOTE:** the name must be a base name, i.e. it cannot contain any slashes "/".
 
 Instantiate the class with `ScanFilter()`
 

src/scan_filter.py

@@ -11,7 +11,7 @@ from sensor_msgs.msg import LaserScan
 class ScanFilter:
 	"""
 	A class that implements a LaserScan filter that removes all of the points.
-	that are not infront of the robot.
+	that are not in front of the robot.
 	"""
 	def __init__(self):
 		# We're going to assume that the robot is pointing up the x-axis, so that
@@ -34,11 +34,11 @@ class ScanFilter:
 
 	def callback(self,msg):
 		"""
-		Callback function to deal with incoming laserscan messages.
+		Callback function to deal with incoming LaserScan messages.
 		:param self: The self reference.
-		:param msg: The subscribed laserscan message.
+		:param msg: The subscribed LaserScan message.
 
-		:publishes msg: updated laserscan message.
+		:publishes msg: updated LaserScan message.
 		"""
 		# Figure out the angles of the scan.  We're going to do this each time,
 		# in case we're subscribing to more than one laser, with different numbers of beams