For example, running for some python code, suggesting that "No module named 'pandas_datareader'", explained the absence of this module.
1. Verify that the absence of the module, first check the existing: pip list or pip3 list, the two are different, a possible installation, do not install in another list
2. No to install: pip3 install pandas_datareader or pip install pandas_datareader
3. pycharm may want to reopen closed (not sure)
4.pycharm import setting, steps: File => Settings => Project Interpreter, click on the right into the "+" sign left list select "pandas_datareader", click under the "Install Package", the installation may take a little time.