Geocoding 40 millions US addresses totally free with PostGIS 2.1 on debian 8
Postgis 2.1 ( on debian 8) make geocoding US addresses ( about 40 Million ) quite easy, and it is totally free! Thanks for the PostGIS and PostGRESQL open source…
K-means clustering and Bisecting K-means in Plain English
K-means clustering is unsupervised machine learning algorithm. Wikipedia has a great demo as below on how it works: Demonstration of the standard algorithm 1. k initial “means” (in this case…
When/where C++ five constructors (copy/assignment/mmove) are invoked
C++ default , copy, move, assignment constructors Sometimes it is confusing where/when the default , copy, move, assignment constructors in C++ are invoked, here some are notes: e.g.: class A…
Bison/Yacc cheat sheet ( Parser Generator cheat sheet)
The same thing happened to bison/yacc, I googled around, and was a little surprised that I could not find a bison/yacc cheat sheet. So I made a very rudimentary one here. Bison-Yacc_cheat_sheet…
Flex cheat sheet (The Fast Lexical Analyzer cheat sheet)
I googled around, and was a little surprised that I could not find a flex/flex cheat sheet. So I made a very rudimentary one here. flex_cheat_sheet Please comment on how to improve…
SVM ( support vecotr machine) in Plain English
(1) Maximum the margin SVM is very easy to understand on the graph,, we just need to find the a separate plane which maximum the margin. see the graph below: (2)…
Quadratic programming in plain English
The big picture is: a quadratic programming problem can be reduced to be a linear programming problem. Here is how: (1) KTT conditions For any non-linear programming: max: f(x), s.t: g(x)…
socat introduction
While searching a command line to write something into a UNIX Domain Socket, I found this great tool called socat which is similar to netcat/samplicator but has more features. The…
Linear programming in plain English
Why study the linear programming (LP) ? LP has a lot of use cases, one of them is the SVM ( support vector machine). The SVM ‘s Lagrangian dual can give…
GDB cheatsheat
GDB cheatsheat There is a good gdb cheatsheet at http://darkdust.net/files/GDB%20Cheat%20Sheet.pdf The output format for print, x is missing there, somehow I think it is useful to add the output formats: x,d,u,o,t,a,f,s,z,r…
