First I tried to update the package according to the documentation using the commands below:
pip install -U scikit-learn
or
conda install scikit-learn
But the version is still 0.18 in PyCharm. Then I tried to run the update in "Settings--Project Interpreter", but failed with this error:
InstallError: Error: one or more of the packages already installed depend on 'conda' and should only be installed in the root environment: conda conda-env. These packages need to be removed before conda can proceed.
I'm totally stuck now. Appreciate any help in advance!