5 ms·

This is exactly the kind of content I love to see -- interesting technical topic, completely outside of any area of expertise of mine, clearly presented, intere

by rdl 11y ago

This is exactly the kind of content I love to see -- interesting technical topic, completely outside of any area of expertise of mine, clearly presented, interesting, and pretty obviously useful. Please post more!

rcpt 11y ago
Hey thanks!
- nailer 11y ago
  Did clarifai have a different company name a few years ago? I built a realtime threaded discussion app with images a few years years ago (like secret or yikyak but in 2011) and used a REST API that was capable of recognising actual body parts. It generally worked well, with the exception of false negatives for cartoon nudity and false positives for pastrami.
  - nailer 11y ago
    Hrm it looks like I was using recogmission / pifilter, which now seems defunct: https://recogmission.wordpress.com/2009/05/01/adult-image-detection-service-pifilter-is-ready/ https://recogmission.wordpress.com/2009/05/01/adult-image-de...
cheez 11y ago
Machine learning, at a high level, is incredibly accessible. The basic technology has been around for a long time and has been taught over and over again.
- activee 11y ago
  Don't you have to have math knowledge ? Any good resource you'd recommend ?
  - cheez 11y ago
    I just realized my version of accessible is in fact... Inaccessible. Sorry, yes the math needed is moderate.
  - taneq 11y ago
    There's "math knowledge" and then there's "math knowledge". I'm still learning the beginner stuff but so far all that it seems to need is basic calculus (ie. "do you understand what a gradient is and how to calculate one numerically?") and some linear algebra ("do you know what matrices are and how to multiply them together?")
    - unixhero 11y ago
      And then there's math knowledge. Social scientist here, and I have no clue of what you're talking about. Calculus destroyed my engineering aspirations.
      - 50CNT 11y ago
        Basic calculus doesn't seem that hard though. You understand asymptotes, right? When something gets closer to a certain value, but doesn't quite touch it, like 1/x with 0. That leads quite naturally to limits, where you say "ok, at a close enough value, we'll just ignore that little bit and say it touches". Then come derivatives. So you have a function graph, and you're trying to determine the slope at a certain point. It's really simple for say y = x, where you just take any two points, but what if the graph is curvy? You'd take the point and then a point close to it, and calculate the slope for that. If the function is fairly smooth, that's fairly close to the actual slope. So you push the other point closer to the original point, and the slope you calculate gets closer to the real slope. You edge closer and closer, and suddenly it sounds a lot like a limit, where your initial point is x, your second point x + h, and h becomes smaller and smaller, so h -> 0. Here's what's cool though. Since you didn't use 5, or 7.23, but x, you can put any point into this, so you've got a function that maps x onto the slope at x of the original function (at least if I remember correctly). You play around with a couple of different kinds of functions and arrive at various rules for differentiating things without having to do the whole limit thing, like x^2 -> 2x, x^3 -> 3x^2, e^x -> e^x, etc. And derivatives are really handy. Say in kinematics, velocity is the derivative over time of position, acceleration is the derivative over time of velocity, and suddenly a whole bunch of things make a lot of sense. Integrals are pretty neat too. So you want to estimate the area under a function from point a to point b. so you draw a box, and there's an area you're missing, or an area you're including but shouldn't, but it's close to the actual area underneath the function. So you think...hrm, I could use two boxes of half the width, that'd be closer to what I want to find. Then three, ten, a hundred, with the sum of the area of boxes getting closer to the actual area. Said more mathy, it'd be a to b, with a width of b-a, and each box gets a width b-a/h, and h gets infinitely large. Then we make that little limit jump again, and get a function. We do that for a couple of functions, deduce some rules, so we don't need to go through the entire process whilst integrating simple functions. a -> x + C, x -> 1/2x^2 + C for example. With some understanding of the FTC (fundamental theorem of calculus), which roughly states that derivatives and integrals are inverse operations of each other (isn't that neat?), it again helps us make sense of things. For example, look at the equations in physics for constant accelerations: v = v_i + at, x = x_i + vt + 1/2at^2. See how v is the integral of a, and x is the integral of v? For the first one, "v_i" is the constant factor C, and "at" is what comes from the factor a. For the second one, "x_i" is the constant factor C, "vt" is "v_i" integrated, and "1/2at^2" is the integral of "at". Calculus is super neat.

by rdl 11y ago

rcpt 11y ago

Hey thanks!

nailer 11y ago
Did clarifai have a different company name a few years ago? I built a realtime threaded discussion app with images a few years years ago (like secret or yikyak but in 2011) and used a REST API that was capable of recognising actual body parts. It generally worked well, with the exception of false negatives for cartoon nudity and false positives for pastrami.
- nailer 11y ago
  Hrm it looks like I was using recogmission / pifilter, which now seems defunct: https://recogmission.wordpress.com/2009/05/01/adult-image-detection-service-pifilter-is-ready/ https://recogmission.wordpress.com/2009/05/01/adult-image-de...

cheez 11y ago

Machine learning, at a high level, is incredibly accessible. The basic technology has been around for a long time and has been taught over and over again.

activee 11y ago
Don't you have to have math knowledge ? Any good resource you'd recommend ?
- cheez 11y ago
  I just realized my version of accessible is in fact... Inaccessible. Sorry, yes the math needed is moderate.
- taneq 11y ago
  There's "math knowledge" and then there's "math knowledge". I'm still learning the beginner stuff but so far all that it seems to need is basic calculus (ie. "do you understand what a gradient is and how to calculate one numerically?") and some linear algebra ("do you know what matrices are and how to multiply them together?")
  - unixhero 11y ago
    And then there's math knowledge. Social scientist here, and I have no clue of what you're talking about. Calculus destroyed my engineering aspirations.
    - 50CNT 11y ago
      Basic calculus doesn't seem that hard though. You understand asymptotes, right? When something gets closer to a certain value, but doesn't quite touch it, like 1/x with 0. That leads quite naturally to limits, where you say "ok, at a close enough value, we'll just ignore that little bit and say it touches". Then come derivatives. So you have a function graph, and you're trying to determine the slope at a certain point. It's really simple for say y = x, where you just take any two points, but what if the graph is curvy? You'd take the point and then a point close to it, and calculate the slope for that. If the function is fairly smooth, that's fairly close to the actual slope. So you push the other point closer to the original point, and the slope you calculate gets closer to the real slope. You edge closer and closer, and suddenly it sounds a lot like a limit, where your initial point is x, your second point x + h, and h becomes smaller and smaller, so h -> 0. Here's what's cool though. Since you didn't use 5, or 7.23, but x, you can put any point into this, so you've got a function that maps x onto the slope at x of the original function (at least if I remember correctly). You play around with a couple of different kinds of functions and arrive at various rules for differentiating things without having to do the whole limit thing, like x^2 -> 2x, x^3 -> 3x^2, e^x -> e^x, etc. And derivatives are really handy. Say in kinematics, velocity is the derivative over time of position, acceleration is the derivative over time of velocity, and suddenly a whole bunch of things make a lot of sense. Integrals are pretty neat too. So you want to estimate the area under a function from point a to point b. so you draw a box, and there's an area you're missing, or an area you're including but shouldn't, but it's close to the actual area underneath the function. So you think...hrm, I could use two boxes of half the width, that'd be closer to what I want to find. Then three, ten, a hundred, with the sum of the area of boxes getting closer to the actual area. Said more mathy, it'd be a to b, with a width of b-a, and each box gets a width b-a/h, and h gets infinitely large. Then we make that little limit jump again, and get a function. We do that for a couple of functions, deduce some rules, so we don't need to go through the entire process whilst integrating simple functions. a -> x + C, x -> 1/2x^2 + C for example. With some understanding of the FTC (fundamental theorem of calculus), which roughly states that derivatives and integrals are inverse operations of each other (isn't that neat?), it again helps us make sense of things. For example, look at the equations in physics for constant accelerations: v = v_i + at, x = x_i + vt + 1/2at^2. See how v is the integral of a, and x is the integral of v? For the first one, "v_i" is the constant factor C, and "at" is what comes from the factor a. For the second one, "x_i" is the constant factor C, "vt" is "v_i" integrated, and "1/2at^2" is the integral of "at". Calculus is super neat.