AttributeError: module 'PyQt5.QtGui' has no attribute 'QMainWindow'

[nguyentuanngoc21]

Describe the bug
I did install PyQt5, but it still requires me to install PyQt4, too
I did try to change the script from using PyQt4 to PyQt5 but it says that "AttributeError: module 'PyQt5.QtGui' has no attribute 'QMainWindow' "

Can you help me to solve the problem between PyQt4 and PyQt5? (seems like I cannot install PyQt4 by somehow)
Thanks anyway.
System observed on:

• Hardware
• OS: Linux 4.4

Reporter Info
Nguyen Tuan Ngoc - University of Science and Technology of Hanoi