title: Ninja is required to load C++ extensions
body: <p>I download a program and want to run it. It's from <a href="https://github.com/zhanghang1989/PyTorch-Encoding" rel="noreferrer">github</a>. </p>
  
  <p>I enter the experiments/segmentation/ folder, and input "python test.py --dataset PContext --model-zoo Encnet_ResNet50_PContext --eval" to the terminal.</p>
  
  <p>The terminal shows "RuntimeError: Ninja is required to load C++ extensions. "
  I have searched the Internet for a night but found no such questions.</p>
  
  <p>Can anybody help me? It's my first time to come here to ask questions</p>