Camille Goudeseune camilleg

Chrono cheat sheet

For the every-day programmer who needs to get shit done instead of fighting type errors.

If your application deals with times in any meaningful way, you should probably want to actually store time_points and durations and what-not; chrono has a pretty rich vocabulary for talking about time-related concepts using the type system. However, sometimes you just need to do something simple, like timing how long something takes, which is where chrono becomes overly complex, hence this cheat sheet.

All examples will assume #include <chrono>.

I just want to time something, then print the result

LightPink1 #ffbdc5 255 189 197 {65535	48573	50629}
pink4 #9d777f 157 119 127 {40349	30583	32639}
pink3 #d7a3ad 215 163 173 {55255	41891	44461}
pink2 #f2b9c4 242 185 196 {62194	47545	50372}
pink1 #ffc3cf 255 195 207 {65535	50115	53199}
HotPink4 #9e4f75 158 79 117 {40606	20303	30069}
HotPink3 #d878a1 216 120 161 {55512	30840	41377}
HotPink2 #f383b5 243 131 181 {62451	33667	46517}
HotPink1 #ff87c1 255 135 193 {65535	34695	49601}
DeepPink4 #9e1e62 158 30 98 {40606	7710	25186}

	# Will take as input a time in seconds (which is typically a result after subtracting two Time objects),
	# and return the result in HH:MM:SS, but instead of resetting HH to 00 when the time exceeds a 24 hour period,
	# it will increase it indefinitely. For other variations, see discussion here: https://gist.github.com/shunchu/3175001
	def formatted_duration(total_seconds)
	total_seconds = total_seconds.round # to avoid fractional seconds to potentially compound and mess up seconds, minutes and hours
	hours = total_seconds / (60*60)
	minutes = (total_seconds / 60) % 60 # the modulo operator (%) gives the remainder when leftside is divided by rightside
	seconds = total_seconds % 60
	[hours, minutes, seconds].map do \|t\|
	# Right justify and pad with 0 until length is 2.

	### JHW 2018
	import numpy as np
	import umap



	# This code from the excellent module at:
	# https://stackoverflow.com/questions/4643647/fast-prime-factorization-module

	import random

	$: (Dollar Colon) is basically a shorthand version of $LOAD_PATH.
	contains an array of paths that your script will search through when using require.
	$0 (Dollar Zero) contains the name of the ruby program being run. This is typically the script name.
	$* (Dollar Splat) is basically shorthand for ARGV. $* contains the command line arguments that were passed to the script.
	$? (Dollar Question Mark) returns the exit status of the last child process to finish.
	$$ (Dollar Dollar) returns the process number of the program currently being ran.
	$~ (Dollar Tilde) contains the MatchData from the previous successful pattern match.
	$1, $2, $3, $4 etc represent the content of the previous successful pattern match.
	$& (Dollar Ampersand) contains the matched string from the previous successful pattern match.
	$+ (Dollar Plus) contains the last match from the previous successful pattern match.