In Machine Learning, we need features for the algorithm to figure
out patterns that help differentiate classes of data. More the
number of features, more the variance (variation in data) and hence
model finds it easy to make ‘splits’ or ‘boundaries’. But not all
features provide useful information. They can have noise too. If our
model starts fitting to this random noise, it would lose its
robustness. So here’s the deal — We want to compose m features from
the available feature space that give us maximum variance. Note that
we want to compose and not just select m features as it is.
In the evening, when working on RSS support for the Python version of
tumblelog, I wanted to know which version of lxml I had installed
via apt-get earlier on. It turned out that the easiest way was to
use dpkg -l python-lxml which reported version 4.3.3-1.
Interested in learning Git? Well you've come to the right place!
"Learn Git Branching" is the most visual and interactive way to
learn Git on the web; you'll be challenged with exciting levels,
given step-by-step demonstrations of powerful features, and maybe
even have a bit of fun along the way.
Just after midnight I finished The Watchmaker's
Glass and Steele Book 1 by C.J. Archer. It has been quite a slow
read. I was hoping on a similar entertaining story as The
but my expectations were not met. I will read the sequel later this
year, because I am curious how the quest for the watchmaker ends.
In this short tutorial, I am going through some of the basic
concepts and commands for Tmux, and how to use a Tmux plugin, which
is called Tmux Resurrect, to
restore Tmux environment after reboot or Tmux server restart.
If you've used any modern Linux distribution, chances are good you
have become familiar with systemd. You might have also happened upon
a systemd issue when an app or service refuses to start. When that's
the case, you might have found yourself in a situation where you're
not quite sure how to begin troubleshooting.
Fortunately for every Linux admin, there's a built-in tool to help
you with that. Said tool is journalctl. Journalctl is the utility
used for querying the systemd logging utility, journald. With the
help of journald and journalctl, you can begin the process of
troubleshooting why a service is refusing to start. Journald also
tracks logs to a specific boot. With this mechanism, you can compare
system boots to see when a service was working properly versus when
In order to make those things explicit, you need a way to express
expected interfaces. One of the first big systems written in Python
was the Zope web framework, and it needed
those things desperately to make it obvious what rendering code, for
example, expected from a "user-like object."
Enter zope.interface, which is developed by Zope but published as a
separate Python package. Zope.interface helps declare what
interfaces exist, which objects provide them, and how to query for
In the evening I tried to build the Wx module under Strawberry Perl 126.96.36.199
inside a virtual machine running Windows 10. After a very long build time
the process failed with: 'my_perl' was not declared in this scope.
One of the biggest and undead myths in SQL is that COUNT(*) is
faster than COUNT(1). Or was it that COUNT(1) is faster than
COUNT(*)? Impossible to remember, because there’s really no reason
at all why one should be faster than the other. But is the myth