I recently created a live GPA calculator as part of a large SPA I’m working on in my day job, but have boiled it down to its bare essence for this widget demo. Try changing the dropdown options here and watch the GPA calculation change in real-time:

View html | View script

In this example, we assume that a student’s current course load comes in over the wire with course names and units. We iterate over the course set and, for all courses being taken for a letter grade, multiply the numeric weight of a predicted grade by the number of units. Those scores get added up, then divided by the total number of units. When a new grade estimate is selected from a dropdown, we need to recalculate the whole aggregate. Let’s step through it.

In the controller, we put data for the course set and a mapping of letter grades to weights onto the current $scope:

  // Letter grades and their weights for the dropdowns
  $scope.gradeopts = [
    {grade: 'A', weight: 4},
    {grade: 'A-', weight: 3.7},
    {grade: 'B+', weight: 3.3},
    {grade: 'B', weight: 3},
    {grade: 'B-', weight: 2.7},
    {grade: 'C+', weight: 2.3},
    {grade: 'C', weight: 2},
    {grade: 'C-', weight: 1.7},
    {grade: 'D+', weight: 1.3},
    {grade: 'D', weight: 1},
    {grade: 'D-', weight: 0.7},
    {grade: 'F', weight: 0}
  ];

  // The student's courses, units and grading options.
  // This would typically come in as JSON data, retrieved via angular's $http
  $scope.schedule = [
    {
      "course_number": "BIO 1A",
      "units": "3.0",
      "grade_option": "Letter"
    },
    {
      "course_number": "COMPSCI 200",
      "units": "4.0",
      "grade_option": "Letter"
    },
    {
      "course_number": "PHIL 201",
      "units": "3.0",
      "grade_option": "Letter"
    },
    {
      "course_number": "ENG 11B",
      "units": "4.0",
      "grade_option": "P/NP"
    },
    {
      "course_number": "HIST 231",
      "units": "2.5",
      "grade_option": "Letter"
    }
  ];

And here’s the HTML that transforms that data into UI, all wrapped in a div with an “ng-controller” attribute

<div ng-controller="GpaController">...

which ties the fragment to a named Angular controller.

    <table>
      <tr>
        <th>Class</th>
        <th>Units</th>
        <th>Grade</th>
      </tr>
      <tr ng-repeat="course in schedule">
        <td>{{course.course_number}}</td>
        <td>{{course.units}}</td>
        <td>
          <!-- In this cell we EITHER show a dropdown for a graded class
          OR an uneditable display of the grading option. Note ng-options
          for converting gradeopts array into dropdown. We only show the
          picklist if the grading option is "Letter grade" (skip pass/no pass classes).
          When a new grade is selected, trigger recalculation of the whole set.
          See http://docs.angularjs.org/api/ng.directive:select
          -->
          <select
            ng-show="course.grade_option=='Letter'"
            ng-model="course.estimated_grade"
            ng-change="gpaUpdateCourse(course, course.estimated_grade)"
            ng-options="g.weight as g.grade for g in gradeopts">
          </select>
          <!-- For non-letter-grade classes, just display the grading type -->
          <span ng-show="course.grade_option!='Letter'">{{course.grade_option}}</span>
        </td>
      </tr>
    </table>

There are some interesting bits in that select element. ng-show ensures that a dropdown will not be displayed if the course is not being taken for a letter grade.

ng-model binds the dropdown to a property of the course object. But if you look at the data source above, you’ll notice that there is no estimated_grade property. That’s because we added that property to each course when the app was first loaded (we’ll get to that in a moment).

And what is the value of that estimated grade? That’s where ng-options comes in. It steps through the gradeopts array and sets values and labels for each of the select options. There’s a gotcha here – if you inspect the DOM and look at the generated select elements, you’ll see that they seem to have simple integer values, not the actual weights we handed them. And yet, when the code is run, g.weight will be substituted in automatically. Angular does this substitution so it can guarantee uniqueness of values and keep track of everything internally. Don’t fight it :)

ng-change is fired whenever a dropdown is changed by the user. It fires the gpaUpdateCourse() function in our controller, which receives the course object and the newly selected grade estimate.

Finally, we display the computed result handed back from Angular, and run it through the built-in “number” directive to limit display of the final estimated GPA to two decimal points. We also provide some fallback text for students who have no classes for some reason.

  <!--
      Use Angular's "number" directive to restrict GPA display to decimals
      || 'N/A' catches the outside case where the student has no letter grade classes
      and therefore no estimated_gpa.
     -->
    <p class="result">Estimated GPA: {{(estimated_gpa | number:2) || 'N/A'}}</p>

    <!-- In case student has no classes at all... -->
    <p ng-show="!schedule.length">
      To calculate your GPA, you must be enrolled
      in one or more classes for the selected semester.
    </p>

In the controller, we have three functions:

First, an initializer to loop through the courses and add an estimated_grade property to each:

  $scope.gpaInit = function() {
    // On init, be generous... start everyone off with a 4.0
    angular.forEach($scope.schedule, function(course) {
      course.estimated_grade = 4;
    });
    $scope.gpaCalculate();
  }(); // Note "()" - makes gpaInit() a self-running function, so it fires on page load

After populating estimated_grade for each course, it kicks off gpaCalculate:

  $scope.gpaCalculate = function() {
    // Recalculate GPA on every dropdown change.
    var total_units = 0;
    var total_score = 0;

    angular.forEach($scope.schedule, function(course) {
      // Don't calculate for pass/no-pass courses!
      // Cast estimates and units to integers before doing math.
      if (course.grade_option === 'Letter') {
        course.score = parseFloat(course.estimated_grade, 10) * course.units;
        total_units += parseFloat(course.units, 10);
        total_score += course.score;
      }
    });

    // The standard GPA calculation formula. estimated_gpa is 
    // bound to the final result paragraph in the html
    $scope.estimated_gpa = total_score / total_units;
  };

The logic there is pretty straightforward. And finally, an update function which is triggered on every dropdown change:

  $scope.gpaUpdateCourse = function(course, estimated_grade) {
    // When a new selection is made, update course object on scope
    // and trigger recalculation of overall GPA
    course.estimated_grade = estimated_grade;
    $scope.gpaCalculate();
  };

And that’s it! A more interesting version of this might take recorded GPAs from previous school terms and calculate an aggregate GPA.

But with spam control settings set to their highest levels, I’ve struggled over the years to keep fall-through spam from reaching the mailboxes of my power users – the spammers  just move too fast,  are too crafty. Spams that look the same from day to day actually have quite different signatures, and manage to evade my arsenal of tools. It’s been incredibly frustrating.

A few months ago, I came up with a set of techniques to let desktop mail clients train the server-side Bayes database about what’s spam and what’s ham. That worked well for a couple of months, but eventually the Bayes dbs became polluted with false hits (probably a result of users incorrectly marking / not marking messages). Is it even possible to operate as an organization smaller than Google and still guarantee low spam levels for users?

Real-time blacklists (RBLs) tap the hive mind – the collective judgement of thousands of human users spread around the world, marking ham and spam every minute of every day. When all of those judgements are collected into a single, continuously evolving database that any host can tap into, it should be possible to create an almost perfect blockade. We know that Akismet has made their RBL work amazingly for weblog comment spam (as I write this, Akismet claims to have blocked 54 million comment spam today alone).

RBLs always seemed like the smartest way to go, but spamhaus and spamcop sure weren’t getting the job done. Doing research in the cPanel forums a few days ago, I discovered that Barracuda Networks, who make a series of firewall appliances for enterprises, maintain their own RBL and provide free access to it for organizations like mine.

Decided to give it a whirl and was blown away. Within 24 hours, the amount of un-tagged spam getting through to my users had dropped to a trickle. I haven’t found an anti-spam tool this effective since… ever. It took almost no effort to set up, and will require almost no effort to maintain in the future. Super stoked.

To the great engineers at Barracuda: The internet thanks you.

Next weekend, our family will ride 25 miles in the American Diabetes Association’s Tour de Cure to help raise money for diabetes research (I wanted to ride 75 miles but it was more important to be able to stay with Miles on his longest ride yet). We are riding because it is an opportunity to change the future and to make a positive impact in the lives of those who are affected by diabetes.

I just signed up to ride in the American Diabetes Association’s Tour de Cure. I’d like to invite you to support me in my efforts to Stop Diabetes!

Tour de Cure is an opportunity to change the future and make a positive impact in the lives of all those affected by diabetes. And it’s a great ride!

Chances are, you also know someone who has been affected by diabetes and you already know how important it is to stop this disease. My goal is to raise . Will you join me by visiting my personal page and making a donation?

By supporting me, you will help the American Diabetes Association provide community-based education programs, protect the rights of people with diabetes and fund critical research for a cure.

The power we have together far outweighs what I can do alone. Please join me by donating to this great cause – it would mean so much to me!

Thank you!

Scot Hacker

P.S. Thank you for considering making a donation to my efforts! Also, if you’re interested in riding, I’d love the company! Visit my personal page or the Tour website for more information.

Update: The ride was fantastic, and all of us completed 25 miles, no sweat. Together, we ended up raising more than $700, strengthened our bodies, and had a great time. Some pics from the day in this Flickr Set.

Meanwhile, a couple bootleg copies of his records somehow made it to South Africa, where his music became the soundtrack for the young adult revolution against apartheid. “Cold Fact” and “Coming From Reality” became record collection staples of pretty much every South African. “If someone had Beatles and Stones records, they had the Rodriguez records too.” In fact, most South Africans will tell you today that Rodriguez was bigger than the Stones in their country.

Originally posted here.

- We loved and used RSS before Google Reader, and we’ll continue to love and use RSS long after it’s gone.

- Google Reader is just another RSS client. OK, its community integration features were unique, but as a pure client, there always have been, and will always continue to be, lots of far superior alternatives.

- This has nothing to do with “the death of open standards.” Nothing is happening to the RSS standard, for godssake.

- What do you expect from free software? A lifetime commitment?

I’ll grant that the big problem here is that Reader has become the default backing store for other clients. In fact, my favorite RSS client by far, Reeder, uses Google Reader as a storage and sync mechanism. Hopefully, Reeder will act quickly to enable other aggregators to fill that role, or to let us add feeds independently of a central aggregator. If it doesn’t, I’ll find one that does. Because, after all, that’s what all RSS aggregators did before Reader existed.

It’s not that big of a loss. RSS lives.

Thank God they spared Orkut.

Update: Reeder has already stated that they’ll live on after the death of Reader.

Here are 50+ Reader replacements either working now or on the horizon.

I’d been thinking our coffee table was long-in-the-tooth — legs squeaked every time we touched it, and not very mobile – wouldn’t it be great to have it on casters so we could wheel it out of the way to play Kinect games?

Decided to have a go at building some furniture.

I had grabbed an old fence gate as part of the booty, and realized it would make a great tabletop. But it was too wide, so started by doing surgery on it to make it narrower.

Overall, the strategy worked well, but by letting a found object dictate the shape of the final product, ended up regretting how close the gate frame was to the table edges.

Had seen a table recently on giant wheels, so thought really big casters could become part of the aesthetic. In the end, wished I had gone even bigger on the casters (might still do that).

Had to do a fair bit of gluing and clamping to take care of splits in the old wood, make it seaworthy for a living room inhabited by a 10-year-old.

Deciding how much paint to strip was a puzzler.

I wanted an “old” look, but at each step in the paint stripping process (outdoors, wearing chemical gloves, thanks), found myself wanting to go farther. Ended up taking it all the way down to bare wood, which I thought looked less junky. Looking back at these pictures, kind of wish I had stopped after the third go-round. But ah well.

Wanted it to have a lower shelf to store magazines, and came up with the idea of running copper pipe between the side legs, and just letting a plank rest on top. Pulled old pipe from the scrap bin at Ace Hardware, and used their pipe cutting tool to get the exact length. First go turned out to be 1/4″ too short, had to make a 2nd trip to get it right (Ace dude said I was the first customer he’d ever seen putting the tools back where I found them!)

Originally planned to strap the shelf to the pipe with leather thong, but decided in the end to just let gravity do its job.

In the end, it’s OK. Really enjoyed the process, but but not totally happy with the result. Wish I hadn’t applied the urethane (I liked the original, lighter color).

Wish the gate frame wasn’t so close to the edges.

Wish I’d picked bigger casters. Wish the legs didn’t end so abruptly. The whole thing just seems more bulky and trashy than what I was going for. But ah well, it’s a learning process.

Doesn’t matter though – feels SO good to work with your own two hands, to turn nothing into something, to end up with something functional. We’ll live with it for a while, see how it goes.

Slideshow:

Flickr set

Schwinn Breeze
 

A couple people asked for sound samples, so here you go – the first compares the banjolele to a modern Kamaka soprano, the other is just a few Velvet Underground riffs.

“The act of crowd-surfing is like the act of couch-surfing – you fall into the audience.” -Amanda Palmer

For a taste, start the audio, then start the slideshow and choose the Full Screen option.

Flickr Set

1) Using Apple or Google Maps, press and hold on the location until a pin is dropped. Tap on the pin’s details to find its “Share” feature, and send the new location to your own email address.

2) From your desktop computer, click the link in the email you receive to open it in Google Maps.

3) In the browser, right-click on the pin and select “What’s Here?” from the menu.

4) The Location field in Google Maps changes from a human-friendly rendering to lat/long.

Presto!

Of course, there are any number of 3rd-party apps you could use to get coordinates directly from the phone – this is assuming you don’t have one of those and just need a quick solution.