Format of .npy files

[rohskopf]

The README.md instructions say to save the data in RAW format, but the current water example uses .npy files.

1. Can we create these files by organizing the data in RAW format, and then using Numpy to save as a .npy file?

2. Does the current version of DeepMD require .npy files, or are they just an option?

[rohskopf]

Just realized the provided bash script, raw_to_set.sh, converts RAW to .npy for us.