Lessons in Algorithms
Nate
Understand the Domain
Typically the requirements are drafted in the context of the domain of the problem that's being solved, or some design aspects are developed from a requirement with domain knowledge applied. I don’t know the first thing about boxing speed bags, so time to do some Googling.
The real nugget I unearthed was that a boxer hits a speed bag, and it makes three contacts with the base: once forward (in punch direction), then it comes all the way back (opposite of punch direction) and strikes the base, and then it goes all the way forward again striking the base (in punch direction). Then the boxer punches it on its way back toward the boxer. This actually gives four opportunities to generate movement to the base, once from the shock of the boxer contacting the bag, and then three impacts with the base.
Now, what I see on the waveforms makes more sense. There isn’t a shock of the bag hitting the base once per punch. My second thought was how many punches can a boxer throw at a speed bag per second. Try as I might, I could not find a straight answer to this question. I found lots of websites with maximum shadow boxing punches and actual punches being thrown maximums but not a maximum for a speed bag. Time to derive my own conclusion: I thought about how far the speed bag must travel per punch and concluded that there must be a minimum amount of force to make the bag travel the distance it needs to impact the base three times. Since I’m not a boxer, all I could do is visualize hitting the bag as slowly as possible and it making three contacts. I concluded from the video in my mind’s eye that it would be difficult to hit a bag less than twice per second. OK, that’s a minimum; how about a maximum? Again, I summoned my mind’s eye video and this time moved my fist to strike the imaginary bag. I concluded with the distance the bag needed to travel and the amount of time to move a fist in and out of the path of the bag that about four per second is all that is possible, even with a skilled boxer. OK, it’s settled. I need to find events in the data that are happening between 2 and 4 hertz. Time to get back to coding and developing!