I don't quite get your terminology, to "add a variable c to center an independent variable Xk", and you've got an extra ) in your equation, so I'm not sure exactly where you want it... If you mean
P(X) = a / (1 + exp(b0 + b1*X1 + .. + bn*Xn) * (Xk - c)) then that's the same as P(X) = a / (1 + exp(b0 + b1*X1 + .. + bn*Xn + log(Xk)/log(c)) replace c by exp(1/bk) and you've got the same old logistic regression, haven't you? On Thu, 31 Jan 2019 at 20:53, Jaap van Kampen <jaapvankam...@gmail.com> wrote: > Hi there! > The standard logistical regression solver > <https://github.com/scikit-learn/scikit-learn/blob/7389dba/sklearn/linear_model/logistic.py#L998> > in scikit-learn assumes the regression equation:<p> > P(X) = 1/ (1 + exp(b0 + b1*X1 + ... + bn*Xn))</p> > .. and solves for the b's using various solver routines. > > For a specific project, I'd like to bound the regression equation between > 0-a (instead of 0-1) and add a variable c to center an independent variable > Xk, e.g.<p> > P(X) = a / (1 + exp(b0 + b1*X1 + .. + bn*Xn) * (Xk - c))) </p> > ... and solve for a, b's and c. > > Any thoughts/ideas on how to modify logistic.py to achieve this? I thought > of modifying the expit > <https://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.special.expit.html>function > to reflect the changed equation. But how do a let the solvers know to also > include the new variables a and c? Any scripts available that are able to > handle my modified logistic regression equation? > > _______________________________________________ > scikit-learn mailing list > scikit-learn@python.org > https://mail.python.org/mailman/listinfo/scikit-learn >
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