Hi there,
I met with a problem:

Description

When I run KernelPCA for dimension reduction for the same datasets, the results are different in signs.

Steps/Code to Reproduce

Just to reduce the dimension to 7 with rbf kernel:
pca = KernelPCA(n_components=7, kernel='rbf', copy_X=False, n_jobs=-1)
pca.fit_transform(X)

Expected Results

The same result.

Actual Results

The results are the same except for their signs:(
[[-0.44457617 -0.18155886 -0.10873474 0.13548386 -0.1437174 -0.057469 0.18124364]]

[[ 0.44457617 0.18155886 0.10873474 -0.13548386 -0.1437174 -0.057469 -0.18124364]]

[[-0.44457617 -0.18155886 0.10873474 0.13548386 0.1437174 0.057469 0.18124364]]

Versions

0.18.1