Wrote the gathering data section of the fitbit blog post.

blogContent/posts/data-science/fitbit.md

@@ -5,10 +5,10 @@ Most people don't need a watch to tell them that they walked a lot
 today or that they got a ton of sleep. As humans we have a pretty good
 gauge of our basic physical health. I am interested in figuring out
 how we can use data science to look at our health data over a longer
-period of time and learn something useful.  
+period of time and learn something useful.   
 
 Lets look at a few things that people typically use Fitbit data for
-before we jump into the weeds.   
+before we jump into the weeds.    
 
 - Setting Goals
 - Motivation
@@ -19,7 +19,7 @@ more frequently. Having something which keeps track of your progress
 is a great motivator. Not only is your daily steps recorded for your
 own viewing, you can share that data with your friends as a
 competition. Although I only have 1 friend on Fitbit, I found that was
-a good motivator to hit the ten thousand steps per day.  
+a good motivator to hit the ten thousand steps per day.   
 
 Goals which are not concrete nearly never get accomplished. Simply
 saying that "I will get in shape" is a terrible goal. In order for you
@@ -30,21 +30,190 @@ step count to fifteen thousand and going to the gym twice a week". One
 goal is wishy washy where the other is concrete and measurable. Having
 concrete data from Fitbit allows you to  quantify your goals and set
 milestones for you to accomplish. Along the way to achieving your
-goal, you can easily track your progress.   
+goal, you can easily track your progress.    
 
 Simply knowing your Fitbit data can help you make some better educated
 decisions about your fitness. By comparing your data against what is
 healthy you can tweak your lifestyle. For example: if you notice that
 you are only getting 6 hours of sleep per night, you can look up the
 recommended amount of sleep and tweak your sleep routine until you hit
-that target.   
+that target.    
 
-Alright, lets do some data science! 
+Alright, lets do some data science!  
 
-![Tom and Jerry Data Science Meme]()
+![Tom and Jerry Data Science Meme](media/fitbit/dataScience.jpg)
 
 # Getting The Data
 
+There are two options which we can use to fetch data from Fitbit. 
+
+
+## Using Fitbit's API
+
+Fitbit has an [OAuth 2.0 web
+API](https://dev.fitbit.com/build/reference/web-api/) that you can
+use. You first have to register your application on Fitbit's website
+to recieve a client ID and a client secret. 
+
+I decided to fetch the Fitbit data using an Express app with node.
+Fetching the  data this way will make it really easy to use on a
+website. Node has tons of NPM modules which makes connecting to
+Fitbit's API really easy. I'm using Passport which is a pretty common
+authentication middleware for Express.  
+
+
+```javascript
+/** express app */
+const express = require("express");
+
+/** Manages oauth 2.0 w/ fitbit */
+const passport = require('passport');
+
+/** Used to make API calls */
+const unirest = require('unirest');
+
+/** express app */
+const app = express();
+
+app.use(passport.initialize());
+app.use(passport.session({
+    resave: false,
+    saveUninitialized: true
+}));
+
+
+var FitbitStrategy = require( 'passport-fitbit-oauth2' ).FitbitOAuth2Strategy;
+
+
+var accessTokenTemp = null;
+passport.use(new FitbitStrategy({
+        clientID:     config.clientID,
+        clientSecret: config.clientSecret,
+        callbackURL: config.callbackURL
+    },
+    function(accessToken, refreshToken, profile, done)
+    {
+        console.log(accessToken);
+        accessTokenTemp = accessToken;
+        done(null, {
+            accessToken: accessToken,
+            refreshToken: refreshToken,
+            profile: profile
+        });
+    }
+));
+
+passport.serializeUser(function(user, done) {
+    done(null, user);
+});
+
+passport.deserializeUser(function(obj, done) {
+    done(null, obj);
+});
+
+passport.authenticate('fitbit', { scope: 
+    ['activity','heartrate','location','profile'] 
+});
+```
+
+Since our authentication middlware is all set up, we just need to add
+the express routes which are required when authenticating.  
+
+```javascript
+app.get('/auth/fitbit',
+    passport.authenticate('fitbit', { scope: 
+    ['activity','heartrate','location','profile'] }
+));
+
+app.get( '/auth/fitbit/callback', passport.authenticate( 'fitbit', {
+    successRedirect: '/',
+    failureRedirect: '/error'
+}));
+
+
+app.get('/error', (request, result) =>
+{
+    result.write("Error authenticating with Fitbit API");
+    result.end();
+});
+```
+
+Now that we are authenticated with Fitbit, we can finally make
+queries.  I created a helper function called queryAPI which attempts
+to authenticate if it is not already authenticated  and then fetches
+the API result from a provided URL.  
+
+```javascript
+const queryAPI = function(result, path)
+{
+    return new Promise((resolve, reject)=>
+    {
+        if(accessTokenTemp == null)
+        {
+            result.redirect('/auth/fitbit');
+            resolve(false);
+        }
+
+        unirest.get(path)
+            .headers({'Accept': 'application/json', 'Content-Type': 'application/json', Authorization: "Bearer " +  accessTokenTemp})
+            .end(function (response)
+            {
+                if(response.hasOwnProperty("success") && response.success == false)
+                {
+                    result.redirect('/auth/fitbit');
+                    resolve(false);
+                }
+                resolve(response.body);
+            });
+    });
+};
+
+app.get('/steps', (request, result)=>
+{
+    queryAPI(result, 'https://api.fitbit.com/1/user/-/activities/tracker/steps/date/today/1m.json').then((data)=>
+    {
+        if(data != false)
+        {
+            result.writeHead(200, {'Content-Type': 'text/html'});
+            result.write(JSON.stringify(data));
+            result.end();
+        }
+        else
+        {
+            console.log("Validating with API");
+        }
+    });
+});
+```
+
+
+## Exporting Data from Website
+
+On [Fitbit's website](https://www.fitbit.com/settings/data/export)
+there is a nice page where you can export your data. 
+
+![Fitbit Website Data Export](media/fitbit/fitbitDataExport.png)
+
+The on demand export is pretty useless because it can only go back a
+month. On top of that, you don't get to download any heart rate data.
+The only data that you do get is aggregated by day. This might be fine
+for some use cases; however, this will not suffice for any interesting
+analysis. 
+
+I decided to try the account archive option out of curiosity. 
+
+![Fitbit Archive Data](media/fitbit/fitbitArchiveData.png)
+
+The Fitbit data archive was very organized and kept meticulous records
+of everything. All of the data was in JSON format and was organized
+nicely in in separate files labeled by date. Fitbit keeps around 1MB
+of data on you per day; most of this data is from the heart rate
+sensors. Although 1MB of data may sound intimidating, it is probably a
+lot less after you store it in a format other than JSON. Since Fitbit
+hires a lot of people for hadoop and SQL development, they are most
+likely using [Apache Hive](https://hive.apache.org/) to store user
+information on the backend. Distributing the data to users as JSON is
+really convenient since it makes learning the data schema very simple.
 
 # Visualizing The Data