I think ... - coding

Install latest Python 3 on Linux CentOS 7

2018-07-07T00:00:00+06:00

Why¶

Not all distro created equal.
Some are created to join the space race, some are to hold unto the leagcy, some are cutting-edge, some are cutting edge. Some are born to boot-up IoT devices some are to push out heavy graphics.

That’s the fun (albeit, power) of Linux.

CentOS 7 is a powerful and stable distro that runs on thousands (probably, millions) production-grade servers.
In the matter of stability, it’s a beast. However, it doesn’t ship with Python 3, by default. You can install it via EPEL repository, or the below simple steps.

Also, take a note. The Python 2 comes with the system, which is probably 2.7.5, do NOT mess with it. Many system components rely on that specific version. If you need the latest versions of 2, use virtualenv or pipenv.

Prepare your system¶

Start with installing pre-requisite utilities for compilation and development support.

$ sudo yum update && sudo yum groupinstall -y "development tools"  
$ sudo yum install -y zlib-devel bzip2-devel openssl-devel ncurses-devel \
       sqlite-devel readline-devel tk-devel gdbm-devel \
       db4-devel libpcap-devel xz-devel expat-devel

Download latest Python source code from Python.org¶

$ wget https://www.python.org/ftp/python/3.6.6/Python-3.6.6.tar.xz
$ tar xf Python-3.6.6.tar.xz
$ cd Python-3.6.6

Enable performance optimizations (optional, but highly recommended)¶

$ ./configure --prefix=/usr/local --enable-shared LDFLAGS="-Wl,-rpath /usr/local/lib"  
$ ./configure --enable-optimizations

Build and install¶

$ make
$ sudo make altinstall

Now, Python 3.6.6 is ready to be used in your system; located in /usr/local/bin/python3.6

$ which python3.6
/usr/local/bin/python3.6

$ python3.6
Python 3.6.6 (default, Jul 10 2018, 14:04:26)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

For convenience, you can create a symbolic-link with a shorter name. If you had system-installed Python3 (unlikely), don’t do this, as some system-components may depend on that specific older version of Python 3.

$ sudo ln -s /usr/local/bin/python3.6 /usr/local/bin/python3
$ python3
Python 3.6.6 (default, Jul 10 2018, 14:04:26)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

Install wheel and pip¶

You don’t need to, because Python 3.6.6 includes these necessary tools included.

$ pip3.6 -V
pip 10.0.1 from /usr/local/lib/python3.6/site-packages/pip (python 3.6)
$ wheel version
wheel 0.29.0

R vs Python — A Summary Comparison

2016-02-08T08:02:00+06:00

..	R	Python
Home	http://r-project.org	http://python.org
Birth	1993	1991
Designer	Ross Ihaka, Robert Gentleman	Guido van Rossum
Package count	7,798 (CRAN)	73,402 (PyPI)
Purpose	statistical computing	General purpose
Paradigm	array, object-oriented, imperative, functional, procedural, reflective	object-oriented, imperative, functional, procedural, reflective
License	GPL	MIT
Platform	cross-platform	cross-platform
Implementations	Main, Rejnin, FastR	cPython, PyPy, Jython, IronPython
TIOBE^TM index	19	5
Dev. IDE	R Studio, Tinn-R, Architect	PyCharm, IPython/Jupyter, Spyder, Komodo IDE
Graphics support	built-in, ggplot2, lattice, Vistat, googleVis	matplotlib, Seaborn, Plotly, Bokeh
Machine-learning	e1071, rpart, igraph, nnet, kernlab, caret	scikit-learn, PyML, PyMC, Shogun
Deep-Learning	H₂O, Darch	TensorFlow, Theano, Decaf, PDNN, Keras, Caffe
Image-Analysis	Raster, EBImage, imager	scikit-image, OpenCV, scipy.ndimage
Github project count	34,268	164,852
Latest release	2015-12-10 (Main: R-3.2.3)	2015-12-21 (cPython: Python 3.4.4)

N.B. * Time-dependent data are up-to-date as of: 2016-02-08 *

…

Open Source as-if You Gonna Die Tonight

2015-12-22T00:00:00+06:00

[ To keep the spirit of this post honest, I am going to publish this blog, immidiately. No draft-ing. This post will be, I hope, under continuous improvement.
This post is available for edit on GitHub, currently in its version 0.0.6 ]

Yes, I mean it. Literally.

I see too many post/comments/blogs, in different meeting-places for techies e.g. hackernews, reddit, etc., which say the same thing:

“I am working on something which I will open-source/publish someday after taking it somewhere.”

See the ambiguous sense in the words?

Unless the code/script/blog you are working on is something sensitive which will make a mess published a “draft” form, you should not wait for “someday”. Or if you have thousands of subscribers to your blog ;)

Or if you decided that you will never publish it in public - that’s an entirely different story.

If it is something of your company’s code-base, commit it in your remote branch, so that your last 19 days of work isn’t just gone just because you are “gone”.

As human, we are far more fragile than we think.

I am not talking about publishing a physical book using a printing press. In that scenario, writers were supposed to write the perfect words, then type it using type-writer to avoid any handwriting-related gotchas. Then it went to the reviewer, then proofreader, then the typesetter makes a block character-by-character. Then comes printing on the paper. The writer had to be sure what he is writing about, ABSOLUTELY. Else, each of the 2000 copies of the first-edition would have the same mistakes.

I am also not talking about pushing the critical code in the production server. That stuff should go through rigorous coding practices, code-reviews, testing etc.

Aside from those cases, this is 2015 - How much does each git push origin gh-pages cost? How much each WordPress post update cost? Or, a single GitHub gist?

Publishing your stuff is free, no matter how many times you update it.

So, why do we think about the paradigm of the printing press when we think of “publishing”?

Frequently shared confusions (FSQ)¶

What if this, my thing, is just plain crap ?
A. Are you sure? You never know for sure. Throw it in the wild. If it is really crap, nobody will remember or hold you responsible for it. How many crappy DaVinci paintings you know? I guess, none. But the Mona Lisa didn’t just appear from thin air. Did it?
This is my toy(or pet) project.
A. Don’t be that selfish kid from the school who don’t let others touch it just because. If you are having fun building something why not let others join in the fun?
This is a one-off script on this ancient COBOL platform, no one is going to need it. Ever.
A. You never know. You are a human. You can’t imagine what people gonna need. Throw it in a gist, just include a suitable title. Add in some comments if you please. May be couple of years later, your script will save someone’s job, and he can still put food on the table. You never know.
If I publish this now some genius with free time will steal my idea and make it something grand without me.
A. Unless you are a big hot-shot with a ground-breaking idea, no one will even notice it. Most genius’ mind is already filled with their own to-do list. Even if they take your idea, let them. Move on. Don’t be a muddy pond, rather be like a river. Rivers don’t dry off due to peasants “stealing” some water.
I haven’t collected my thoughts enough to make this post a grand one yet.
A. Don’t think too high yourself. Let others do that for you.
No project is born grand, and no great man born great. Your contributions is what goes ahead. You the person? Not so much. Time passed along “Romeo & Juliet”, but Shakespeare is dead and gone.
I am special. My words/code should be special, perfect, coherent like a pearl-necklace. (yes, we all feel like that, we just don’t acknowledge it publicly.)
A. No, you are not. You are not a special unique snowflake. See the previous answer.
Who the ***k are you to tell me what to do?
A. It’s not about me, I am nobody. Just a open-source enthusiast who wants to see more and more open-source projects, scripts, blog-posts which haven’t gone to grave with their mortal creators. I’m just sharing my own thoughts about it. It is your code on your own personal-pc, after all.

Why should I open my source(post/thoughts/etc) tonight?¶

You can literally die tonight. Then all of your pet-projects are just gone. ‘Cause probably none in your family is in coding business or they aren’t sure about your intention.
Tomorrow morning, your mind will just drift-away.
What is a vivid idea tonight that could impact thousands of people’s lives, tomorrow morning will become a faded, will-do-it-someday idea. One month after tonight, you probably will probably be oblivious about your own idea, draft, script, code.
It’s a mind-trick to force ourselves to work on something to avoid public shame. We feel obliged to correct errata that is in public, but something hidden away in a private, hidden, local folder we don’t have to feel bad about.

To avoid embarrassment¶

Make sure your audience (or colleagues for that matter) know the content’s status. Put a “prelude” section mentioning the half-done condition. Better yet, use some version number.
Make your genereal idea clear. For code, point out what it is and what it is supposed to do. For a blog, present the basic idea at least, even if it is not with perfect grammer.

How infrastructure can improve¶

Open-source mainstream hosting platforms e.g. Github, Bitbucket, GitLab etc. could have a “Open the source” trigger-switch for individual projects where a software developer can enable the trigger with some condition like:

“Open the source” if I don’t login GitHub for 1 year (which means I am dead or I’ve gone crazy trying to remember GitHub)
“Open the source” on a pre-set date e.g. 2020-02-20

[dear reader, thanks a lot for reading up to here. I am sure there are many points missing on this post. Also, as English is not my first language, hence there must some misused words or phrase. But you get the idea. Please comment/criticise/point out the missing stuff. I will try to discuss, update, correct that.]

Contributors¶


Khaled Monsoor	initial author, maintainer
Wayne Werner	editor (v.0.0.3 → v.0.0.4)

Python - How to Create All Possible Combinations (a.k.a Permutations)

2014-01-31T00:00:00+06:00

Let’s say the number is 123.

Then the statement:

[int(''.join(x)) for x in permutations(list(str(123)))]

will create a sorted list of all possible numbers using ‘1’,‘2’ and ‘3’. which is, [123, 132, 213, 231, 312, 321]

What it is doing¶

The part, permutations(list(str('123' is creating a permutated tuples’ list of splitted string ‘123’. And the int(''.join(x)) is converting each tuple to Integer.

However, of course, you need to import permutations from itertools.

so, the generalized version would be:

from itertools import permutations
[int(''.join(x)) for x in list(permutations(list(str(n))))]

Python is fun. Isn’t it?