Add option to choose customise filename for find_B_method='omfit'

[valerian-chen]

Right now, find_B_method='omfit' does not allow for custom filenames, unlike the other methods, which allow an input_filename_suffix

Sorry @ZedThree, this should be quite easy to change but I don't quite understand the notation: f"topfile{input_filename_suffix}"

The new way of doing paths does boggle me a little, embarrassingly.

[ZedThree]

This is using an f-string (official docs, tutorial), it's basically a fancier way of doing "topfile" + input_filename_suffix.

It's maybe a little overkill here, but they're really handy for more complex cases like (made up example):

filename = "data_" + suffix + "_" + str(shot_number) + "_" + str(launch_freq_GHz) + "GHz"

and using an f-string:

filename = f"data_{suffix}_{shot_number}_{launch_freq_GHz}GHz"

Hopefully you'll agree the second one is easier to read -- it also happens to be significantly faster, although that only matters if you're doing this in a big loop for some reason.

Basically, if you need to construct a string, f-strings are almost always the best choice (the exception is if you want a template to fill in later).

I guess here you probably want:

@@ -2393,7 +2393,7 @@ def create_magnetic_geometry(

     elif find_B_method == "omfit":
         print("Using OMFIT JSON Torbeam file for B and poloidal flux")
-        topfile_filename = magnetic_data_path / "topfile.json"
+        topfile_filename = magnetic_data_path / f"topfile{input_filename_suffix}.json"

         with open(topfile_filename) as f:
             data = json.load(f)

[valerian-chen]

Ah wait that's how I've been formatting filenames with floats. Didn't realise it worked with strings too. This is great, thank you so much!

Definitely agree this is nicer.