Baffling Science bafflingscience

Tabs and Windows

Function	Shortcut
New Tab	`⌘` + `T`
Close Tab or Window	`⌘` + `W` (same as many mac apps)
Go to Tab	`⌘` + `Number Key` (ie: `⌘2` is 2nd tab)
Go to Split Pane by Direction	`⌘` + `Option` + `Arrow Key`
Cycle iTerm Windows	`⌘` + `backtick` (true of all mac apps and works with desktops/mission control)

	Part	Description
	47-011053-004	Deflection Chain Gear w/Bearing Complete
	11-051772-001	Lockwasher (12 mm)
	47-011130-004	Bearing Bolt
	47-011245-003	Lower Chain Guide
	11-052601-001	Carriage Bolt (8 mm x 30 mm)
	11-051704-001	Hex Nut (8 mm)
	11-051770-001	Lockwasher (8 mm)
	47-011135-000	N.A. Elevator Frame w/Felt Backing
	47-011276-003	Upper Chain Guide

Mixed Markdown and Shell Scripting

: By the power of this magic string: ex: set ft=markdown ;:<<'```shell' #, this file is now both a markdown document and an executable shell script. chmod +x it and try running it!

The above line does just what it says. More specifically, when placed within in the first 5 lines and preceded only by blank lines or #-prefixed markdown headers:

The first part of the magic string makes github and various editors (e.g. atom with the vim-modeline packge) treat the file as having markdown syntax (even if the file doesn't have an extension)
The second part (if run in a shell), makes the shell skip execution until it encounters the next ```shell block.

(The line also has to start with a : so that it's valid shell code.)

Get/set ID3 meta tags using ffmpeg

A quick guide on how to read/write/modify ID3 metadata tags for audio / media files using ffmpeg.

FFmpeg has a free-form command line option that allows the user to specify key-value-pairs for encoding metadata. Let's take a look.

1. Read ID3 metadata

To list all global metadata tags for a media file, just set an input but no output file.

How to download your Udemy course videos using youtube-dl

$ youtube-dl --list-extractors | grep udemy

Steps

Get link to the course to download. e.g. https://www.udemy.com/course-name/
Login into udemy website, save the cookie from chrome using Chrome (Cookie.txt)[1] export extension. Save it to file udemy-cookies.txt
Get the link of the video that you want to download. usually in format. Use the command provided below where you have to replace the {course_link} and {path_to_cookies_file} with respective paths.

$ youtube-dl {course_link} --cookies {path_to_cookies_file}

Useful Pandas Snippets

A personal diary of DataFrame munging over the years.

Data Types and Conversion

Convert Series datatype to numeric (will error if column has non-numeric values)
(h/t @makmanalp)

	#!/usr/bin/env ruby

	print "What is the URL of your Apple Downloads resource?\nURL:"
	url = gets.strip

	print "What is the ADCDownloadAuth cookie token:\nADCDownloadAuth: "
	token = gets.strip

	command = "aria2c --header \"Host: adcdownload.apple.com\" --header \"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8\" --header \"Upgrade-Insecure-Requests: 1\" --header \"Cookie: ADCDownloadAuth=#{token}\" --header \"User-Agent: Mozilla/5.0 (iPhone; CPU iPhone OS 10_1 like Mac OS X) AppleWebKit/602.2.14 (KHTML, like Gecko) Version/10.0 Mobile/14B72 Safari/602.1\" --header \"Accept-Language: en-us\" -x 16 -s 16 #{url} -d ~/Downloads"

	# One liner
	wget --recursive --page-requisites --adjust-extension --span-hosts --convert-links --restrict-file-names=windows --domains yoursite.com --no-parent yoursite.com

	# Explained
	wget \
	--recursive \ # Download the whole site.
	--page-requisites \ # Get all assets/elements (CSS/JS/images).
	--adjust-extension \ # Save files with .html on the end.
	--span-hosts \ # Include necessary assets from offsite as well.
	--convert-links \ # Update links to still work in the static version.

	'''
	Using OpenCV takes a mp4 video and produces a number of images.

	Requirements
	----
	You require OpenCV 3.2 to be installed.

	Run
	----
	Open the main.py and edit the path to the video. Then run:

	if exists("*ToggleBackground") == 0
	function ToggleBackground()
	if &background == "dark"
	set background=light
	else
	set background=dark
	endif
	endfunction

	command BG call ToggleBackground()