Kang-Li (Stephen) Cheng kanglicheng

Install MongoDB on macOS Sierra

This procedure explains how to install MongoDB using Homebrew on macOS Sierra 10.12.
Official MongoDB install documentation: here

Install Homebrew

Installing Homebrew is effortless, open Terminal and enter :
$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

Clarify and agree on the scope of the system

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

Large Scale Distributed Deep Networks

Introduction

In machine learning, accuracy tends to increase with an increase in the number of training examples and number of model parameters.
For large data, training becomes slow on even GPU (due to increase CPU-GPU data transfer).
Solution: Distributed training and inference - DistBelief
Link to paper

DistBelief

Papers

This list is adapted from the lecture plan for the "Advanced Topics in Computer Systems" course at Berkeley, which is available here: https://people.eecs.berkeley.edu/~kubitron/cs262/index_lectures.html

Thanks to Anthony Joseph and John Kubiatowicz for putting the original list together.

Introduction to the course, some basic philosophy, UNIX system.

Django/Python Questions

Find the most frequent integer in a list, Test list : [3,5,6,3,9,0,3,8,3,1,3]

Find the common elements of 2 lists

    a = [2,3,4,1,1,3,6]
    b = [2,8,9,1,3]

Django Migrations without Downtime

The following instructions describe a set of processes allowing you to run Django database migrations against a production database without having to bring the web service down.

Note that in the below instructions, migrations are all run manually at explicit points, and are not an automatic part of the deployment process.

Adding Fields or Tables

Adding a (nullable) field or a new table

Make the model or column addition in your code.

My implementation of the Gale/Shapley algorithm in Python. This algorithm is designed to address the Stable Marriage Problem.

Compare this recursive variant with the implementations on Rosetta Code.

Problem description

Given an equal number of men and women to be paired for marriage, each man ranks all the women in order of his preference and each women ranks all the men in order of her preference.

A stable set of engagements for marriage is one where no man prefers a women over the one he is engaged to, where that other woman also prefers that man over the one she is engaged to. I.e. with consulting marriages, there would be no reason for the engagements between the people to change.

Set up Django, Nginx and Gunicorn in a Virtualenv controled by Supervisor

Steps with explanations to set up a server using:

Virtualenv
Virtualenvwrapper
Django
Gunicorn

This guide assumes that you recently run brew upgrade postgresql and discovered to your dismay that you accidentally bumped from one major version to another: say 9.3.x to 9.4.x. Yes, that is a major version bump in PG land.

First let's check something.

brew info postgresql

The top of what gets printed as a result is the most important:



	# Given a board and an end position for the player, write a function to determine if it is possible to travel from every open cell on the board to the given end position.

	board1 = [
	[ 0, 0, 0, 0, -1 ],
	[ 0, -1, -1, 0, 0 ],
	[ 0, 0, 0, 0, 0 ],
	[ 0, -1, 0, 0, 0 ],
	[ 0, 0, 0, 0, 0 ],