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How-to: (Linear ...) regression in Sage

asked 2011-03-15 14:42:53 +0200

tmaxara gravatar image

Suppose I have the following set of points r = [(1,2),(3.45,4),(6,5),(4,3)]. How do I implement in Sage a (linear) regression with "bord tools"?

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Can you clarify 'bord tools'? I'm not familiar with this phrase.

kcrisman gravatar imagekcrisman ( 2011-03-15 15:45:49 +0200 )edit

I don't know what "bord tools" means, but you can do all kinds of regression analysis, including linear regression, using the Sage interface to R. There are experts lurking here that I'm sure can give you an example.

benjaminfjones gravatar imagebenjaminfjones ( 2011-03-15 15:53:46 +0200 )edit

I bet it is a translation from French: "avec les outils du bord". It means : using only what already exists in Sage.

Laurent Claessens gravatar imageLaurent Claessens ( 2011-03-16 13:51:16 +0200 )edit

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answered 2011-03-16 16:18:35 +0200

kcrisman gravatar image

It turns out that this has even showed up on Stack Overflow.

Luckily, that page refers to the function I had completely forgotten about - find_fit.

sage: find_fit?

String Form:    <function find_fit at 0x10bee5cf8>
Namespace:      Interactive
File:           /Applications/MathApps/sage/local/lib/python2.6/site-packages/sage/numerical/
Definition:     find_fit(data, model, initial_guess=None, parameters=None, variables=None, solution_dict=False)
       Finds numerical estimates for the parameters of the function model
       to give a best fit to data.

So this might work, and looks decent.

sage: R = [[1,2],[3.45,4],[6,5],[4,3]]
sage: var('a,b')
(a, b)
sage: model(x) = a*x+b
sage: find_fit(R,model)
[a == 0.56881365890949054, b == 1.445160655902004]
sage: points(R)+plot(model(a=find_fit(R,model)[0].rhs(),b=find_fit(R,model)[1].rhs()),(x,0,10),color='red')

If you are serious about your needs, though, you should probably use some of the tools in Scipy or R (numerous YouTube videos on this, though for reason I can't watch them right now.

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nice find @kcrisman!

niles gravatar imageniles ( 2011-03-16 16:41:45 +0200 )edit
DSM gravatar imageDSM ( 2011-03-16 22:39:45 +0200 )edit

Thank you for your answer

tmaxara gravatar imagetmaxara ( 2011-03-26 17:45:09 +0200 )edit

answered 2012-08-04 15:07:56 +0200

Andre Mikulec gravatar image
    mydata = [[1,3],[2,7],[3,13],[4,24]]
    mymodel(x) = a*x^2 + b*x + c 
    myfit = find_fit(mydata,mymodel,solution_dict=True)
    points(mydata,color='purple') + plot(
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answered 2017-10-06 16:44:29 +0200

this post is marked as community wiki

This post is a wiki. Anyone with karma >750 is welcome to improve it.

Any way to find the Correlation Coefficient r and the Coefficient of Determination r^2 using find_fit()? TIA, AJG (

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Welcome to Ask Sage. Please post this as a new question rather than as an answer here (then delete the answer here). Avoid checking the "community wiki" checkbox on Ask Sage.

slelievre gravatar imageslelievre ( 2017-10-06 23:31:49 +0200 )edit

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Asked: 2011-03-15 14:42:53 +0200

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Last updated: Aug 04 '12