chore: renamed files under diffpy.snmf/examples to avoid repetition

[TingwenZhang]

Removed the repetition between folder names and file names under diffpy.snmf/examples.

├── mix-ZnSe-w0.4-BaTiO3_c-w0.6/
│ ├── mix-w0.4-w0.6-1.iq
│ ├── mix-w0.4-w0.6-2.iq
│ └── ...
└── mix-ZnSe-w0.5-BaTiO3_c-w0.5/
├── mix-w0.5-w0.5-1.gr
├── mix-w0.5-w0.5-2.gr
└── ...

These files only exist under diffpy.snmf/examples and are not referenced anywhere else in the repository.

@sbillinge @john-halloran
Could you look at my suggestions on renaming?

[sbillinge]

@TingwenZhang nicely done there. Maybe something like mix-ZnSe-BaTiO3-0.5-0.5 might be better. It is also scalable. If we always only have two components we only need one of the 0.5's but if we have a mix of three things this could extend to mix-ZnSe-BaTiO3-NaCl-0.3-0.3-0.4 for example. Of course, one of the fractions is redunant always, but less confusion is probably worth the extra typing. That would be my take.

The filenames only need to be 1.gr, 2.gr etc. in principle but having a bit more is probably safer. ZB.5-1.gr or something. Is the last integer just an index or does it indicate something else like temperature?

[TingwenZhang]

Yes, the last integer is just an index in the original files 1-20. The shortest name would be <index>.gr, since the folder name specifies all of the contents.

[sbillinge]

Yes, the last integer is just an index in the original files 1-20. The shortest name would be <index>.gr, since the folder name specifies all of the contents.

As I mentioned, although just <index>.gr is the minimum naming required, I suggested a slightly longer name as a better tradeoff between typing redundancy and clarity...please see above.

[TingwenZhang]

I made the names more descriptive. I also added w before every fraction because mix-ZnSe-BaTiO3_c-0.5-0.5-1.gr may be confusing at the 0.5-0.5-1 part (I think mix-ZnSe-BaTiO3_c-w0.5-w0.5-1.gr is more clear). Also because these namings specify we are using weight fraction rather than atomic fraction.

[sbillinge]

I am sorry @TingwenZhang you didn't quite understand. I was after:

mix-ZnSe-BaTiO3-0.5-0.5/ZB.5-1.gr
...

The shortened filename is clear given the directory name.

To avoid multiple commits of many files, could we do this on a new PR?