I’ve seen several interesting blog posts related to MIT switching from Scheme to Python for their intro course. This is really interesting to me since SICP is one of my favorite CS books of all time. Nevertheless I’m glad to see leading institutions change to my favorite language.

Paraphrase of Gerald Sussman’s remarks

Dan Weinreb’s blog

The other day I discovered that the folks working on VPython have been very busy over the last couple of years. I had given up on VPython because the Mac distribution was so difficult to use. It required the X windows server and one point and lots of other extra junk at other times. But now things are easy! There is a great installer package and it just works.

For those of you who have not heard of VPython before it is a 3D graphics module called visual built on top of Python and OpenGL. You can do a lot of nice 3D graphics very simply with VPython. Its great for education in math and physics and introductory computer science.

So as an experiment I built a turtle graphics module on top of VPython. I use turtle graphics a lot in teaching but the TKinter turtles all suffer from some event loop problems when you use them with IDLE. VPython does not suffer from this problem plus gives you a lot of other cool benefits. One of the benefits is that the window resizes automatically for you based on the units you use in your application. Want to draw a picture at the atomic level of detail? No problem, want to draw planets circling each other? Again no problem.

Here’s a screen capture of a fractal tree created in 3-D using my new turtle.

Here’s the VPython turtle code:

def tree(t,trunkLength):
    if trunkLength < 5:
        return
    else:
        turnDz = random.randint(20,40)
        turnDx = random.randint(20,40)
        trunkShort = random.randint(10,20)
        t.width(trunkLength/10.0)
        if trunkLength < 25:
            t.color(color.green)
        else:
            t.color((174/255.0,145/255.0,0))
        t.forward(trunkLength)
        # right trunk
        t.right(turnDz,ZAXIS)
        tree(t,trunkLength-trunkShort)
        # left trunk
        t.left(2turnDz,ZAXIS)
        tree(t,trunkLength-trunkShort)
        # front trunk
        t.right(turnDz,ZAXIS)
        t.right(turnDx,XAXIS)
        tree(t,trunkLength-trunkShort)
        # back trunk
        t.left(2turnDx,XAXIS)
        tree(t,trunkLength-trunkShort)
        # restore
        t.right(turnDx,XAXIS)
        t.backward(trunkLength)

If you want to check out the turtle module and play with it, you are welcome to do so: hg clone bitbucket.org/bnmnetp/v… Or send me mail.

Here’s a little plug for our book from our Colleague Mark Guzdial at Georgia Tech. This was written last September right after the book was published but I didn’t find out about it until this morning. Thanks Mark!

In addition, David and I have started a new blog to post corrections and updates to Python Programming in Context Over here If you are already using the book please check it out.

Intro

Once I could add tasks to my RTM account through LaunchBar I wanted a way to quickly pull up a view of what tasks were due today through LaunchBar. The Growl library provides a nice way of doing this.

The overview is as follows: Activate LaunchBar and type due. This due is installed as a search shortcut and you can search for today, tomorrow, or all (abbreviations are also easy). The search shortcut runs the python script that searches your tasks on Remember the Milk. For each task it finds it puts up a sticky Growl notification so you get a nice list of tasks on your screen. You could easily customize the script to put all the tasks in a single notification but I like them separate.

Since the Growl module registers this script as an application you can also use the Growl Preference Pane to customize the look and feel or even the location of your notifications. You can also customize whether you want the notifications to be sticky or not.

The Code

Here is the code for doing all of this. It makes use of the filter parameter on getList.

#!/usr/bin/env python

from rtm import *
import sys
import Growl

def sendNotify(ts):
    if type(ts.task) == list:
        for j in range(len(ts.task)):
            notifier.notify("today","Task Due: "+ts.task[j].due[:10],ts.name,sticky=True)
    else:
        notifier.notify("today","Task Due: "+ts.task.due[:10],ts.name,sticky=True)

if len(sys.argv) == 2:
    command = sys.argv[1]
else:
    command = "today"

apiKey = "get your own"
secret = "this too"
token = "You will create this"

name = "RTMDue"
notifications = ["today","tomorrow"]
notifier = Growl.GrowlNotifier(name,notifications)
notifier.register()

if command[:3] == "tod" or command == '':
    cutoff = 'today'
elif command[:3] == "tom":
    cutoff = 'tomorrow'
else:
    cutoff = None 

rtm = createRTM(apiKey, secret, token)

if cutoff:
    filterString = 'status:incomplete and (due:%s or dueBefore:%s)'%(cutoff,cutoff)
else:
    filterString = 'status:incomplete'

theTasks = rtm.tasks.getList(filter=filterString)

if type(theTasks.tasks.list) == list:
    for i in range(len(theTasks.tasks.list)):
        if type(theTasks.tasks.list[i].taskseries) == list:
            for j in range(len(theTasks.tasks.list[i].taskseries)):
                ts = theTasks.tasks.list[i].taskseries[j]
                sendNotify(ts)
        else:
            ts = theTasks.tasks.list[i].taskseries
            sendNotify(ts)
else:
    if type(theTasks.tasks.list.taskseries) == list:
        for i in range(len(theTasks.tasks.list.taskseries)):
            ts = theTasks.tasks.list.taskseries[i]
            sendNotify(ts)
    else:
        ts = theTasks.tasks.list.taskseries
        sendNotify(ts)

Next Steps

It would be great if I can figure out a way to have the Growl notification box call a script to mark the task as done. Feel free to leave comments or suggestions or improvements in the comments.

For the trip to Silicon Valley I wanted to have everyone be able to twitter about the experience using their own twitter account, but I also want to have a central place for everyone following the trip as a whole to see all of our tweets. How to do that? Python and the Twitter API to the rescue. You can see the results of this by checking out @lutherlive on twitter

import twitter

USER = “Your group account”
PASS = “your group password”
TAG = “tag contained in each message”

api = twitter.Api(username=USER,password=PASS)

# figure out when my last post was
statuses = api.GetUserTimeline(user=USER)
last_post = statuses[0].GetCreatedAt()

# Get the timelines for all friends since my last_post
tl = api.GetFriendsTimeline(user=USER,since=last_post)
for post in tl:
    # since my posts may show up in friends timelines avoid reposting loop
    if post.user.screen_name != USER and TAG in post.text:
        api.PostUpdate(post.user.screen_name + “: " + post.text)

This little script logs in using the twitter account you create for the group. Importantly, this account must follow all of the group members that you want to be able to re-tweet. When one of the group members wants a tweet to show up on the group account they must use the TAG, in our case @lutherlive, somewhere in their post.

After logging in, the script grabs the timeline for all of the members of the group. This timeline is restricted to the posts since the last a post was made by the group user. This is important to do otherwise you would end up with duplicate re-tweets every time the script is run.

Next the script simply loops over all of the posts and checks for the tag. If the tag is in the post the post is updated along with the screen name of the original group member that made the post.

I put the script into a cron-job on the computer science server at Luther to run every 15 minutes, so while the @lutherlive user isn’t a real time reflection of its group members tweets, its pretty darn close.