Least squares fit of a surface in Python (with ridiculous application)

http://pingswept.org/2009/06/15/least-squares-fit-of-a-surface/

by pingswept • 17 years ago

72 19 17 years ago

icey• 17 years ago

It would have been much cooler if you'd included a picture of the stack of masonite inverted so we could see the actual topology. Otherwise, pretty awesome.

pingswept6• 17 years ago

An excellent point. I finished the masonite cutting around midnight on Sunday, the garage where I did the cutting was too dark for a good picture, and I wanted to see if it was going to work.

It did look cool with all the contours showing.

lutorm• 17 years ago

That's more permanently (and aestethically) corrected by ripping up the floor and re-leveling it... But I grant that would be more work.

paulgb• 17 years ago

It would also be less pythonic.

avigesaa• 17 years ago

It looks like the platform rests on the edges of the masonite. I wonder if it will leave depressions in the hardwood floors underneath? Assuming they don't own the place, their security deposit may help pay for the proper fix.

pingswept6• 17 years ago

Yeah, I'm a little worried about that.

For better or for worse, we do own the place. I've thought that I might add a single flat sheet of masonite under the contours as protection, but that would involve another trip to the store and pulling the whole thing apart again, so maybe not.

axod• 17 years ago

Laying a shaggy carpet would have probably have been easiest ;)

edrtfgdr• 17 years ago

Are we still allowed to express surprise that anyone who would choose such a geeky solution has a girlfriend? Or have we all grown up?

pavel_lishin• 17 years ago

I think we're allowed to express surprised at the fact that the girlfriend would put up with a relatively unaesthetic solution to this problem.

Although I guess in the end they'll probably cover up the bare materials with something nice. Maybe a rug.

pingswept6• 17 years ago

You will be gratified to know that the first suggestion that "the girlfriend" made was to cover it with a rug.

saurabh• 17 years ago

Very cool indeed. Is there a list of people like him that I can follow? Waking up to something this nerdy would make my day.

pingswept6• 17 years ago

I think the list you speak of is called "Hacker News."

Glad you liked it. I actually went and stood on the platform for about 30 seconds this morning, just to experience the joy.

petercooper3• 17 years ago

This reminds me of the tale about the US spending millions of dollars to build a pen that would work in zero gravity. After it was made, it was noted the Russians simply used pencils!

The parallel here is to get a chair without wheels. I find all these calculations interesting as a geek but in terms of the efficiency of the task, "fail" :)

pingswept6• 17 years ago

I am familiar with this "chair without wheels" technology you mention. The slope is steep enough that the tilt is still annoying, but a chair with legs of unequal length might have solved that.

The efficiency was, however, very close to 100%. You're just measuring the wrong thing.

petercooper3• 17 years ago

we have found that this is steep enough to make a desk chair roll– kind of irritating

The only premise I could sense was related to the rolling.

The efficiency was, however, very close to 100%. You're just measuring the wrong thing.

As you seem to have focused on how fun the exercise was, you are more than likely right.

andrewl• 17 years ago

The space pen story is not true, according to Snopes:

http://www.snopes.com/business/genius/spacepen.asp

petercooper3• 17 years ago

Agreed, and an interesting link. That is why I called it a tale.

chime• 17 years ago

Very clever approach. But my big concern is that the floor is not level to begin with. If it's because the wood flooring was laid poorly, then fine. However, if it's because the floor structure itself is bowing down due to the weight, then I would be very concerned. Hope it's just a cosmetic deficiency and not structural defect.

pingswept6• 17 years ago

From what I can tell (I'm the owner of the house), the first 6 feet of the floor were built slanted. A friend of mine with some contracting expertise has suggested that the room was likely a porch that was later closed in; such a slant would be typical for an exterior floor to shed rain. The flooring also changes slightly in how it's nailed down around the 6 foot mark, suggesting that the underlayment might change there too.

Least squares fit of a surface in Python (with ridiculous application)

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