Re: [Numpy-discussion] Upper and lower envelopes

2008/9/30 bevan <bevan07@gmail.com>:

Hello,

I have some XY data. I would like to generate the equations for an upper and lower envelope that excludes a percentage of the data points.

I would like to define the slope of the envelope line (say 3) and then have my code find the intercept that fits my requirements (say 5% of data below the lower envelope). This would then give me the equation and I could plot the upper and lower envelopes.

I hope this makes sense. Thanks for any help.

For this particular problem - where you know the slope - it's not too hard. If the slope is b, and your points are x and y, compute y-b*x, then sort that array, and choose the 5th and 95th percentile values. Anne