Init commit of speech to text tutorial.

example_8.md

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+# Example 8
+
+This example will showcase how to save the interpreted speech from Stretch's [ReSpeaker Mic Array v2.0](https://wiki.seeedstudio.com/ReSpeaker_Mic_Array_v2.0/) to a text file.
+
+
+<p align="center">
+  <img src="images/respeaker.jpg"/>
+</p>
+
+
+
+Begin by running the `sample_respeaker.launch` file in a terminal.
+```bash
+# Terminal 1
+roslaunch respeaker_ros sample_respeaker.launch
+```
+
+Then run the speech_text node.
+
+```bash
+# Terminal 2
+cd catkin_ws/src/stretch_tutorials/src/
+python speech_text.py
+```
+
+The ReSpeaker will be listening and will start to interpret speech and save the transcript to a text file.  To stop shutdown the node, type **Ctrl** + **c** in the terminal.
+
+### The Code
+```python
+#!/usr/bin/env python
+
+import rospy
+import os
+from speech_recognition_msgs.msg import SpeechRecognitionCandidates
+
+class SpeechText:
+    """
+    A class that saves the interpreted speech from the ReSpeaker Microphone Array to a text file.
+    """
+    def __init__(self):
+        """
+        Initialize subscriber and directory to save speech to text file.
+        """
+        self.sub = rospy.Subscriber("speech_to_text", SpeechRecognitionCandidates, self.callback)
+        self.save_path = '/home/hello-robot/catkin_ws/src/stretch_tutorials/stored_data
+    		rospy.loginfo("Listening to speech.")
+
+    def callback(self,msg):
+        """
+        A callback function that receives the speech transcript and appends the
+        transcript to a text file.
+        :param self: The self reference.
+        :param msg: The SpeechRecognitionCandidates message type.
+        """
+        transcript = ' '.join(map(str,msg.transcript))
+        file_name = 'speech.txt'
+        completeName = os.path.join(self.save_path, file_name)
+
+        with open(completeName, "a+") as file_object:
+            file_object.write("\n")
+            file_object.write(transcript)
+
+if __name__ == '__main__':
+    rospy.init_node('speech_text')
+    SpeechText()
+    rospy.spin()
+```
+
+
+### The Code Explained
+Now let's break the code down.
+
+```python
+#!/usr/bin/env python
+```
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+
+
+```python
+import rospy
+import os
+```
+
+You need to import rospy if you are writing a ROS Node.
+
+```python
+from speech_recognition_msgs.msg import SpeechRecognitionCandidates
+```
+
+Import SpeechRecognitionCandidates from the speech_recgonition_msgs so that we can receive the interpreted speech.
+
+```python
+def __init__(self):
+    """
+    Initialize subscriber and directory to save speech to text file.
+    """
+    self.sub = rospy.Subscriber("speech_to_text", SpeechRecognitionCandidates, self.callback)
+```
+
+Set up a subscriber.  We're going to subscribe to the topic "speech_to_text", looking for SpeechRecognitionCandidates messages. When a message comes in, ROS is going to pass it to the function "callback" automatically.
+
+```python
+self.save_path = '/home/hello-robot/catkin_ws/src/stretch_tutorials/stored_data
+```
+
+Define the directory to save the text file.
+
+```python
+transcript = ' '.join(map(str,msg.transcript))
+```
+
+Take all items in the iterable list and join them into a single string named transcript.
+
+```python
+file_name = 'speech.txt'
+completeName = os.path.join(self.save_path, file_name)
+```
+
+Define the file name and create a complete path directory.
+
+
+```python
+with open(completeName, "a+") as file_object:
+    file_object.write("\n")
+    file_object.write(transcript)
+```
+
+Append the transcript to the text file.
+
+```python
+rospy.init_node('speech_text')
+SpeechText()
+
+```
+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 "/".
+
+Instantiate the class with `SpeechText()`
+
+```python
+rospy.spin()
+```
+Give control to ROS.  This will allow the callback to be called whenever new
+messages come in.  If we don't put this line in, then the node will not work,
+and ROS will not process any messages.

src/speech_text.py

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+#!/usr/bin/env python
+
+# Import modules
+import rospy
+import os
+
+# Import SpeechRecognitionCandidates from the speech_recognition_msgs package
+from speech_recognition_msgs.msg import SpeechRecognitionCandidates
+
+
+class SpeechText:
+    """
+    A class that saves the interpreted speech from the ReSpeaker Microphone Array to a text file.
+    """
+    def __init__(self):
+        """
+        Initialize subscriber and directory to save speech to text file.
+        """
+        # Initialize subscriber
+        self.sub = rospy.Subscriber("speech_to_text", SpeechRecognitionCandidates, self.callback)
+
+        # Create path to save captured images to the stored data folder
+        self.save_path = '/home/hello-robot/catkin_ws/src/stretch_tutorials/stored_data'
+
+        # Create log message
+        rospy.loginfo("Listening to speech.")
+
+    def callback(self,msg):
+        """
+        A callback function that receives the speech transcript and appends the
+        transcript to a text file.
+        :param self: The self reference.
+        :param msg: The SpeechRecognitionCandidates message type.
+        """
+        # Take all items in the iterable list and join them into a single string
+        transcript = ' '.join(map(str,msg.transcript))
+
+        # Define the file name and create a complete path name
+        file_name = 'speech.txt'
+        completeName = os.path.join(self.save_path, file_name)
+
+        # Append 'hello' at the end of file
+        with open(completeName, "a+") as file_object:
+            file_object.write("\n")
+            file_object.write(transcript)
+
+
+if __name__ == '__main__':
+    # Initialize the node and name it speech_text
+    rospy.init_node('speech_text')
+
+    # Instantiate the SpeechText class
+    SpeechText()
+
+    # Give control to ROS.  This will allow the callback to be called whenever new
+    # messages come in.  If we don't put this line in, then the node will not work,
+    # and ROS will not process any messages
+    rospy.spin()