Question

In Kernel trick method, We do not need the coordinates of the data in the feature space

Answer 1

In Kernel trick method ,we do not need the coordinates of the data in the feature space.

The way we have to apply the kernel trick is whenever a data point say x is used by an algorithm.

The x is used in the expression in the form and we take z as the other point.

The problem for optimization is - maxαi∑iαi−12∑i∑jαiαjyiyjxTixj

Answer 2

Thank you for asking this question, here is your answer:

No, we do not. The prerequisite to apply the kernel trick is that wherever the algorithm uses a data point x, it is used in an expression of the form xTz, where z is some other point.

The corresponding prediction function, once α’s are known, is given by:

y=f(x)=∑iαiyixTix

If there is any confusion please leave a comment below.