Underlying our approach to this subject [computer programming] is our conviction that “computer science” is not a science and that its significance has little to do with computers. The computer revolution is a revolution in the way we think and in the way we express what we think. The essence of this change is the emergence of what might best be called procedural epistemology—the study of the structure of knowledge from an imperative point of view, as opposed to the more declarative point of view taken by classical mathematical subjects. Mathematics provides a framework for dealing precisely with notions of “what is.” Computation provides a framework for dealing precisely with notions of “how to.”

• https://math.hws.edu/javanotes/c5/s4.html
• https://codereview.stackexchange.com/questions/161773/object-oriented-design-of-card-deck
• https://www.infoworld.com/article/2077217/card-engine-in-java.html
• https://www.geeksforgeeks.org/design-data-structuresclasses-objectsfor-generic-deck-cards/
• http://homepage.divms.uiowa.edu/~slonnegr/oosd/22OOD.pdf
• http://techdive.in/java/card-game-using-java
• https://github.com/tssovi/grokking-the-object-oriented-design-interview/blob/master/object-oriented-design-case-studies/design-blackjack-and-a-deck-of-cards.md

and for dice game

• https://codereview.stackexchange.com/questions/40919/basic-java-dice-game

And a VERY cool and useful alternate Java Textbook https://math.hws.edu/javanotes/index.html

Some Needed Installs...

Brew

• Visit https://brew.sh/.
• Follow the directions under "Install Homebrew".

JDK 18.0.1

• Visit Oracle's download page for the Oracle JDK.
• Download the dmg for Java JDK 18.
• Use the downloaded dmg to install the application.
• (double click the DMG to install)

JDK 1.8

• Visit https://builds.openlogic.com/downloadJDK/openlogic-openjdk/8u332-b09/openlogic-openjdk-8u332-b09-mac-x64.pkg
• and install that PKG file.

IntelliJ

• Download the dmg for the Community version for Mac.
• Visit JetBrains' download page for IntelliJ.
• Use the downloaded dmg to install the application.
• Did YOU install the COMMUNITY edition? (not the Pro)

How would you write a class and a method to do this? How do you read in the string expression, figure out what it means and then calculate and return the answer?

Take a look at each of the tests below and ponder how you might build such a class. How would you break this problem down into phases that can be called one after another to go from a string argument expr to a double return value.

package rocks.zipcode;

import static org.junit.Assert.*;

public class CalculateTest {

    @org.junit.Before
    public void setUp() throws Exception {
    }

    @org.junit.After
    public void tearDown() throws Exception {
    }

    @org.junit.Test
    public void runSimple() {
        Calculate engine = new Calculate();

        String args2 = "( 4 + 5 )";
        double expected = 9.0;
        double actual = engine.run(args2);
        assertEquals(expected, actual, 0.0001);
    }
    @org.junit.Test
    public void runAlexTest() {
        Calculate engine = new Calculate();

        String args2 = "( -4 + 5 )";
        double expected = 1.0;
        double actual = engine.run(args2);
        assertEquals(expected, actual, 0.0001);
    }

    @org.junit.Test
    public void runSimpleRPN() {
        Calculate engine = new Calculate();

        String args2 = "( 4 5 + 7 3.0 / * )";
        double expected = 21.0;
        double actual = engine.run(args2);
        assertEquals(expected, actual, 0.0001);
    }

    @org.junit.Test
    public void runFailedTestNoParens() {
        Calculate engine = new Calculate();

        String args2 = "4 + 5";
        double expected = 9.0;
        double actual = engine.run(args2);
        assertNotEquals(expected, actual, 0.0001);
    }

    @org.junit.Test
    public void runSimple2() {
        Calculate engine = new Calculate();

        String args2 = "( ( 4 + 5 ) * ( 7 / 3.0 ) )";
        double expected = 21.0;
        double actual = engine.run(args2);
        assertEquals(expected, actual, 0.0001);
    }

    @org.junit.Test
    public void runSimple3() {
        Calculate engine = new Calculate();

        String args2 = "( sqrt ( 2.0 ) * sqrt ( 5.0 ) )";
        double expected = 3.162277660;
        double actual = engine.run(args2);
        assertEquals(expected, actual, 0.0001);
    }

    @org.junit.Test
    public void runLongerDemo() {
        Calculate engine = new Calculate();

        String args2 = "( ( ( 4 + 5 ) * ( 7 / 3.0 ) ) - ( 13 / 6.0 ) )";
        double expected = 18.833333333;
        double actual = engine.run(args2);
        assertEquals(expected, actual, 0.0001);
    }

    //( ( 5 + ( 3 * 8 ) ) – ( 2 * 7 ) )

    @org.junit.Test
    public void runFromReadme() {
        Calculate engine = new Calculate();

        String args2 = "( ( 5 + ( 3 * 8 ) ) - ( 2 * 7 ) )";
        double expected = 15;
        double actual = engine.run(args2);
        assertEquals(expected, actual, 0.0001);
    }


}

And then, and be careful, do not plagarise code:

• https://github.com/iluwatar/java-design-patterns
• https://github.com/javaee-samples/javaee8-samples
• https://github.com/phishman3579/java-algorithms-implementation

And the last of these, well, it's quite a beautiful thing.

Now, who the hell is Joshua Bloch and why should you pay attention to things he says?

How to Write a Git Commit Message

Commit messages matter. Here’s how to write them well.

cbeamscbeams

How to make a nice looking github account page

How to Create an Impressive GitHub Profile README - SitePoint

Did you know you can create a stunning GitHub profile README page? Learn how to add images, social and blog links, GitHub stats, and more.

SitePointNida Khan

Google Style Guides

Style guides for Google-originated open-source projects

styleguide

Handy. Very handy.

Web sites

These were just used to show how much info there is out there.

• Market Stats https://philly.curbed.com/2017/4/7/15209526/philadelphia-housing-rental-statistics-pew-report
• Redfin - https://www.redfin.com/city/15502/PA/Philadelphia/housing-market

BUT I particularly liked these Aaron Kreider Maps: http://www.campusactivism.org/philly/value.php

• NOTICE this site also has a number of other maps views along the bottom of the pages here.

But then a really good site for Data related to housing in the City of Philadelphia: Property web site: https://property.phila.gov/

Getting a handle on a property and its neighborhood

Sample of Data Analytics for a target property

• square footage property values for houses near by
• there are some analytics you can do
• Use Property web site to produce CSV files of property local/near to the address you are researching
• a CSV file (“comma separated values”) is a common data file and one that can be used in lots of ways.
• Property allows you to find the values of a specific property you are investigating

you can then get the CSV file and put it into Google Sheets to tinker with.

• look at the rows with $1 transfer values as they will skew the averages. you might consider removing those rows.

add averages to the formulas in the cells at the bottom of the sheet.

• to learn how to do that, here is a tutorial on averaging data in a column https://www.lifewire.com/google-spreadsheets-average-function-3123872
• average property value by adding a formula to the cell at the bottom of the column
• DIVIDE average value by square footage

These numbers

• can give you per-ft2 number for your other project financials
• can help you decide which properties meet your risk profile.

Data Engineering Tools

Google Sheets is decent.

The easiest way is to get a gmail account (for free, if you don’t have one)

• https://accounts.google.com/
• look for Create account link
• lets you use google sheets and save docs there

PHA Lottery Properties:

Can be used as samples for the links above. These addresses were taken from the PHS Lottery of last December.

2933 W MASTER ST

3033 W STILES ST

3041 W STILES ST

623 W JEFFERSON ST

3222 N ETTING ST

63 E SEYMOUR ST

To access the "cluster’s API" server from our local machine, we only need to get the kubeconfig file created on the node during the setup.

$ mkdir ~/k8s
$ cd ~/k8s
$ sudo cat /etc/rancher/k3s/k3s.yaml > k3s.yaml

We then need to change the server key so it references the remote IP address of node1 instead of the localhost.

$ sed -i '' "s/127.0.0.1/$IP/" k3s.yaml

Finally, we configure our local kubectl so it uses the kubeconfig file (k3s.yaml) we’ve just retrieved. A simple way is to set the KUBECONFIG environment variable so it points towards the configuration file.

$ export KUBECONFIG=$PWD/k3s.yaml

And maybe you should put this into your ~/.bashrc

Session 2

Let's setup a different power user on the Pi.

Once your Raspberry PI 4 completed booting Raspbian, you can remotely connect to it with SSH. Open your terminal and type this command:

ssh pi@raspberrypi.local

This logs in the pi user. Keep in mind that the default password is raspberry (unless you've changed it).

Create a new user and delete the pi user

As you noticed in the previous session, the default user in Raspbian is pi with password raspberry. Everyone that ever played with a Raspberry PI knows this. Thus it is highly recommended to change the password for the pi user as soon as possible. My personal recommendation is to take this a step further: create a new user and delete the pi user altogether.
To create a new user, run the command:

sudo adduser newusername

Replace newusername with the username of your preference. The command prompts you to enter some basic information about the new user, including the password. You can leave any of this blank, except the password. The password should be a strong one.

As a next step, add the new user to the same groups as the pi user belongs to (just excluding the pi group itself). The following one-liner pipes together a few commands to achieve this. (This should all be on ONE line in the terminal)

groups | sed 's/pi //g' | sed -e "s/ /,/g" | xargs -I{} sudo usermod -a -G {} newusername

Before actually removing the pi user, close the current SSH connection and establish a new one. This time login as the newly created user:

ssh newusername@raspberrypi.local

After verifying that you can login as the new user, it is time to remove the pi user, including its home directory:

sudo deluser --remove-home pi

Now we have a new user, one that has all the same privileges of the pi user without the world guessing what your username is.

Read some about Luigi and how to do pipeline/workflow stuff in standard python leveraging a package like Luigi. Then use your understanding to look into how Airflow works.

• Luigi
  • https://luigi.readthedocs.io/en/stable/example_top_artists.html
• Link luigi to airflow
  • https://www.kdnuggets.com/2019/03/data-pipelines-luigi-airflow-everything-need-know.html

Then, read these airflow articles to help support what you're seeing about Airflow.

• Airflow Articles
  • Step by step: build a data pipeline with Airflow
  • Build Data Pipelines with Apache Airflow
  • Building a Production-Level ETL Pipeline Platform Using Apache Airflow
  • Airflow Tutorial
  • Airflow Template Repo

Often times, early in cohorts, students begin to discover two things. The first is that materials they are using are incomplete, vague and contain mistakes or errors that cause confusion. The second thing is that some students discover that these revelations disturb them a great deal.

One of the unfortunate aspects of a life spent coding is that you're most often dealing with incomplete information or data, incomplete or inarticulate (badly written) documentation, tests that are unreliable, specifications which are not specific, requirements that are vague, incomplete or misleading, and sometimes, just sometimes, actually deliberate disinformation meant to disrupt your work.

The best advice we can offer is this: "don't let it bother you". Or as an early ZCW instructor used to say "get over it right now".

State of the Art

Software is still - in spite of decades of global effort by all kinds of computer scientists, engineers, and coders - an art. (Some would argue it is not clear it can be engineered either.) Perhaps the most important software book(s) of the last 50 years is Donald Knuth's The Art of Computer Programming (which is currently at 5 volumes and 9998 pages). And if Prof. Knuth says it's an Art, rest assured it is.

So the precision which many people expect coding/programming to have in creation and maintenance is simply not there. Sure, we can approach some kind of formality of method, with practice, but alas, ours is not precise field. Detailed yes, complex yes, but error-free and "bug free" - no way.

Bugzilla

To handle the "metadata" of bugs, special programs are developed to maange the database aspects of tracking all the brokenness that exists in software.

Bugzilla was an early bug tracking system for large software systems and products. It was used to track issues, features, desires, errors, and of course, bugs. All software has bugs, seeking to reduce the number of bugs in an application is very desirable; but it is a moving target. We need bug trackers like Bugzilla. So much so that Github has issue tracking built into every repository. Many places used Bugzilla for years, some still do. It had this quirk, inserted deliberately, of "zarro boogs"

Zarro Boogs

Bugzilla returns the string "zarro boogs found" instead of "0 bugs found" when a search for bugs returns no results. "Zarro Boogs" is intended as a 'buggy' statement itself (a misspelling of "zero bugs") and is thus a meta-statement about the nature of software debugging, implying that even when no bugs have been identified, some may exist.

The following comment is provided in the Bugzilla source code to developers who may be confused by this behaviour:

Zarro Boogs Found

This is just a goofy way of saying that there were no bugs found matching your query. When asked to explain this message, Terry Weissman (an early Bugzilla developer) had the following to say:
I've been asked to explain this ... way back when, when Netscape released version 4.0 of its browser, we had a release party. Naturally, there had been a big push to try and fix every known bug before the release. Naturally, that hadn't actually happened. (This is not unique to Netscape or to 4.0; the same thing has happened with every software project I've ever seen.) Anyway, at the release party, T-shirts were handed out that said something like "Netscape 4.0: Zarro Boogs". Just like the software, the T-shirt had no known bugs. Uh-huh. So, when you query for a list of bugs, and it gets no results, you can think of this as a friendly reminder. Of course there are bugs matching your query, they just aren't in the bugsystem yet...
— Terry Weissman
From The Bugzilla Guide – 2.16.10 Release: Glossary

So, strive to make software better, but software is never perfect. And it is truly hubris to think you can make it perfect; the nemesis of bugs is the only result. Only three things are certain: death, taxes, software bugs, and off-by-one-bugs.

Before the OS Concepts lecture, I'd like you to watch these videos.

They break down the complexities of the CPU, Memory and so on within a modern microprocessor. They move at a decent pace, and explain pretty clearly quite a few concepts you need to understand before you can really get WHY an Operating System for a computer is such an important concept. Things like Windows, Linux, Android, iOS and MacOS each perform largely the same services for software written on top of them. But how does the bits of a program actually get interpreted (or decoded) into action deep inside the processor?

This is about an hour and 45 minutes of videos. Get some popcorn and a glass of wine, sit back and...

Early Computing
Electronic Computing
Boolean Logic and Logic Gates
Representing Numbers and Letters with Binary
Calculation - the ALU
Registers & RAM
The Central Processing Unit
Instructions & Programs

And at this point, think not about the 1-core, 8-bit CPU you've been conceptualizing in these videos; let's think about a 4-core, 64-bit machine. Everywhere you had things moving around using 8-bit bytes, start thinking about a 64-bit word (that's right, 8 bytes or 64-bits move all at once). All wthin a single core, but then let's add 3 more cores, and now we have something approaching a modern smart phone CPU...

Wondrous Strange, eh?

Cellular Automata.

• https://bitstorm.org/gameoflife/ good sim on page, several great patterns pre-built.
• https://www.quantamagazine.org/john-conways-life-in-games-20150828/ bio of Conway, plus good desc of game.
• https://web.stanford.edu/class/sts145/Library/life.pdf bad PDF of 1970 SciAm article
• https://www.ibiblio.org/lifepatterns/october1970.html very simple version of 1970 SciAm article.
• https://web.stanford.edu/class/sts129/Alife/html/Life.htm 1990's page of Life, with bad HTML.
• https://en.wikipedia.org/wiki/Conway's_Game_of_Life wikipedia on Life.