LAPI, VINCENT J, ATTLABS wrote: > Hi, > Please bear with me as I am new to Python and have not done any > programming in about 20 years. I am attempting to do a simple > interpolation of a line's intermediate points given the x,y coordinates > of the line's two endpoints within an Active State Python script that I > am working with. Is there a simple way to do this simple interpolation > in the Active state Python 2.4 that I have or do I need to get Numeric > Python? And where do I get it? > Thanks, > Vince Lapi > You shouldn't really *need* Numeric (NumPy or numpy, nowadays) for a relatively simple problem like that, since the formulae involved are pretty simple.
Given known points on the line at (xa, ya) and (xb, yb) then for any point (x, y) on the line we get y = ya + ((x - xa) * (yb - ya))/(xb - xa) So you just need to plug the values for x and the known points into the formula to get the interpolated value of y. If you are interpolating a non-linear formula through a number of samples clearly there'd be a little more jiggery pokery involved to identify the particular interval on which interpolation is required, but nothing horrendous. Numpy, which is derived from the old Numeric code, is at http://numpy.scipy.org/ should you wish to investigate its features. It probably has better-than-linear interpolation algorithms in it. Note that if you decide to download it you should choose the Python 2.4 version - extensions coded in compiled languages are specific to a particular version of the language. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://del.icio.us/steve.holden Blog of Note: http://holdenweb.blogspot.com See you at PyCon? http://us.pycon.org/TX2007 -- http://mail.python.org/mailman/listinfo/python-list
