programmingstudies

[programmingstudies]

How I got mouse sensitivity to work in Ubuntu 17

I could only find Trackpad sensitivity in the GUI settings. I followed this and this to set the mouse sensitivity for a cheap wireless mouse I picked up.

I used this one to customize the scroll speed.

[programmingstudies]

NumPy vs Linear Algebra

I quickly noticed that "Vector" in programming languages ≠ "vector" in mathematics" and that "you should rather learn how to translate math to the code."

Particularly, NumPy's notion of vectors and and their transposition differs from that in linear algebra.

I'll be referring to this post (partially quoted below) in the future.

For example, transposing a NumPy array of shape (a,b,c,d) returns an array of shape (d,c,b,a) -- the axes are reversed. In two dimensions, this means an array of shape (a,b) (i.e. a rows, b columns) becomes an array of shape (b,a) (i.e, b rows, a columns). So NumPy's notion of transposition matches up nicely with the linear algebra notion for 2-dimensional arrays.

NumPy apes the concept of row and column vectors using 2-dimensional arrays. An array of shape (5,1) has 5 rows and 1 column. You can sort of think of this as a column vector, and wherever you would need a column vector in linear algebra, you could use an array of shape (n,1). Similarly, wherever you see a row vector in linear algebra you could use an array of shape (1,n)

[programmingstudies]

Hoztel Jaipur, India

I've been studying machine learning. On my iPhone 5s. Watching various lectures on YouTube, including those from Andrew Ng's ML Course, and reading from Steven Marsland's Machine Learning - An Algorithmic Perspective text. Filling in gaps in my linear algebra and calculus knowledge as necessary. I've been here for just over a week. Today I asked the hostel owner if I could install Python on the computer available for guest use. He said "don't install 2.7."

I installed Anaconda v5 and am up and running with Jupyter notebooks and Python 3.6! I went briefly through a NumPy tutorial to get the feel of typing back in my fingers. It felt good to be writing code again, however basic!

I'm excited to implement some of the basic ML algorithms I've been learning about, including multivariate linear regression, logistic regression, gradient descent, and the multi-layer perceptron. This will bring me up to the state of the art as of the early 1970s.

Exciting times!

[programmingstudies]

Seems like once you learn linear algebra and calculus the gates really start to open up to some cutting edge stuff. “Prior knowledge of quantum mechanics is helpful but not required.”

[programmingstudies]

Excellent explanation

[programmingstudies]

Math v programming

In generalizing a solution to the problem of “given a free throw percentage F, find the probability P of making exactly K out of N free throw attempts,” I am reminded that programming follows after knowing what to program — in this case after having figured out the mathematical model. With programming it is possible to run simulations to quickly gain intuition by exploring the possible outcomes for different values and/or visualizing these data.

P(K out of N free throws) = F^K * (1 - F)^(N - K) * N!/(N-K)!K!

where the first and second terms are the probabilities of making and missing the requisite number of free throws and the third is the number of such unordered combinations of makes/misses.

From here I begin to wonder at the generalization of making at least K out of N free throws. Via programming it would be trivial to map & reduce the above model over an array of values of K..N. But I wonder if there’s a magic math formula to accomplish the same in the absence of either a runtime or the desire to sum many terms by hand, say for the question of probability of at least 70/100 free throws given a 56% shooter.

[programmingstudies]

Removing Byte Order Marks

To remove all byte order marks in a directory I used this solution: http://www.yiiframework.com/wiki/570/remove-byte-order-mark-bom-from-files-recursively/

grep -rl $'\xEF\xBB\xBF' . > file_with_boms.txt while read l; do sed -i '1 s/^\xef\xbb\xbf//' $l; done < file_with_boms.txt rm file_with_boms.txt

[programmingstudies]

Thought

Do you ever get the sense that we're all just map functions?

[programmingstudies]

Ubuntu middle mouse button

Just spent a bunch of time trying to find a terminal for ubuntu where I could select to copy and click to paste. I found that Terminator allegedly offered this, so I got it, but then in my installed version it didn't work. What gives?

It turns out my OS had been setup to not register the middle mouse button "as the middle mouse button" -- and this is the button both my existing terminal (ROXTerm) and Terminator both use to paste.

I determined this by trying to get Terminator to copy + paste as desired and bumping into this post about a hack that referenced button numbers. Then I searched for "ubuntu mouse test" and discovered the utility program xev that shows that button numbers for the mouse buttons as you click them. My left button was 1, right was 3, and middle was... 10? How'd that get there? According to this it is possible to remap the physical button output using the somewhat cryptic xmodmap.

Running xmodmap -pp shows the current mapping of Physical Button Numbers to Button Codes. Running xmodmap -e "pointer = 1 2 3 4 5 6 7 8 9 10" remapped all of the physical buttons up to 10 (for me the only ones that were mismapped were 2 and 10) to their respective Button Codes.

Bonus

I've written about this before, but I use jumpapp to run or raise the terminal -- this involves creating a custom keyboard shortcut to jumpapp terminator, for example.

[programmingstudies]

Infrastructure

Jenkinsfile -> Makefile -> Dockerfile -> package.json -> app_start.js

^ infra

[programmingstudies]

http://curtclifton.net/papers/MoseleyMarks06a.pdf

(courtesy of the wrath of the leaky abstraction!)

[programmingstudies]

Once a technology has been introduced into a company, someone has to keep it alive as long as it is in use. The costs of the latest and greatest technology are not just in initial production development, or even entirely in development at all. The costs have to include the cost of building and maintaining the competence to keep the technology alive.

Kent Beck, Extreme Programming Explained (1st Editino)

[programmingstudies]

Great, great post

We can learn about life generally from such a refactoring discipline.

http://ronjeffries.com/xprog/articles/refactoring-not-on-the-backlog/

Sometimes people call this "technical debt". It really isn't: it's really just not very good code. But it doesn't look too bad -- yet.

We are tempted to ask for time from our product owner to refactor. Often, that time is not granted: we're asking for time to fix what we screwed up in the past. Not likely anyone is going to cut us any slack on that.

We take the next feature that we are asked to build, and instead of detouring around all the weeds and bushes, we take the time to clear a path through some of them. Maybe we detour around others. We improve the code where we work, and ignore the code where we don't have to work. We get a nice clean path for some of our work. Odds are, we'll visit this place again: that's how software development works.

[programmingstudies]

from Functional Programming in Scala, chapter 1

A modular program consists of components that can be understood and reused independently of the whole, such that the meaning of the whole depends only on the meaning of the components and the rules governing their composition; that is, they are composable.

As we'll learn, any function with side effects can be split into a pure function at the "core" and possibly a pair of functions with side effects; one on the input side, and one on the output side. ... This transformation can be repeated to push side effects to the "outer layers" of the program. Functional programmers often speak of implementing programs with a pure core and a thin layer on the outside that handles effects. We will return to this principle again and again throughout the book.

[programmingstudies]

If

I was just working through this Clojure tutorial and came upon the "Watch Out!" section where the authors point out that the plain old if statement in Java/C# doesn't evaluate to anything -- and hence, it must have a side-effect in order to do something! Whereas in Clojure, if is an expression that evaluates to a value -- the functional if functions identically to the ternary operator in Ruby/JavaScript/C# and other languages.

I also found interesting that declarative vs imperative is orthogonal to functional.

Additionally, the Anti-If Campaign.

[programmingstudies]

Multiple envs with Python

I've tried getting up an running with machine learning so many freaking times now I think I've completely screwed up my home ubuntu machine, as far as like where all the different python stuff is installed. Well today I made a giant leap in organizativity!

Use virtualenv! It's freaking easy!

sudo pip install virtualenv

Create an env in a dir

virtualenv ENV_NAME

Load the env

source ENV_NAME/bin/activate

Check it

which python which python3

Install the things for the tensorflow tutorial

pip3 install --upgrade tensorflow pip3 install --upgrade matplotlib

Run the tutorial!

Deactivate the virtualenv

deactivate

Rejoice in modularity!

[programmingstudies]

Ubuntu: always open same terminal

Get this app: https://github.com/mkropat/jumpapp Use Keyboard to create a custom shortcut to launch a terminal. For example I use roxterm so I created

Name: launch terminal Command: jumpman roxterm

Now this keyboard shortcut always opens the same terminal window!