Underdefined inputs while using PCA about raven HOT 1 CLOSED

From wangc on gitlab:

Currently, we do not have an error checking for that. I think if the PCA transformation leads to unrealistic inputs, the application code should catch that. This is because the requirements of inputs are usually determined via the application code, not RAVEN. In addition, if the user chooses too few transform variables, one way we can do is to implement the posteriori error checking, but this needs further discussion. I think this issue is related to the PCA method itself, not the algorithm. I suggest to change the label from defect to improvement. @talbpaul

from raven.