Q: What is the inverse of regularization strength in Logistic Regression? How should it affect my code?
A: Regularization is applying a penalty to increasing the magnitude of parameter values in order to reduce overfitting. When you train a model such as a logistic regression model, you are choosing parameters that give you the best fit to the data. This means minimizing the error between what the model predicts for your dependent variable given your data compared to what your dependent variable actually is.

The problem comes when you have a lot of parameters (a lot of independent variables) but not too much data. In this case, the model will often tailor the parameter values to idiosyncrasies in your data -- which means it fits your data almost perfectly. However because those idiosyncrasies don't appear in future data you see, your model predicts poorly.

To solve this, as well as minimizing the error as already discussed, you add to what is minimized and also minimize a function that penalizes large values of the parameters. Most often the function is λ∑θj2, which is some constant λ times the sum of the squared parameter values θj2. The larger λ is the less likely it is that the parameters will be increased in magnitude simply to adjust for small perturbations in the data. In your case however, rather than specifying λ, you specify C=1/λ

解釋的很清楚，原來C是正則化因子的倒數(shù)