Queries reagding basics of PCA : I want to use PCA for the feature selection with CNN features. From the theory of PCA, the data should correlated. After extracting the features from CNN the features are organized is this way [f1 f2 f3 f4 f5 f6] and the corresponding labels are [L1 L1 L2 L2 L3 L3]. How can I check my data is correlated? and if the data is not correlated than how can I make one?