Input file writing

[wpbonelli]

Flopy must be able to write ASCII files and do so efficiently. That said, it is reasonable to recommend external binary data for maximum performance.

This topic is related but not identical to #49.

[wpbonelli]

From @deltamarnix

We were discussing how XArray and CAttrs would work together like in this PR: #62 .

cattrs will always return a dictionary of some sort, so that it can be passed into packages like pyyaml or tomlkit. cattrs provides the conversion for datetimes and encoding. But cattrs is not made for file-io, because when you would want to convert everything into one big string, that would all be passed into memory in a single instance.

It would be better to use functionality like jinja for file writing and just pass it the actual python instance of simulation / model / package. We can write filter functions that can handle the dask chunking while writing large datasets from a netcdf file / lazy dask array. This is something we still need to prototype.

Some preliminary benchmarks here.

[wpbonelli]

Some thoughts on the topic of parity between flopy3 and flopy4 input files... in general we want to shoot for functionally identical, with possible cosmetic differences?

Floating point precision:

• determine what existing conventions flopy3 has for floating point precision in input files (and if not adequately documented, do so)
• decide on flopy4 floating point precision output conventions

Other possible criteria to consider:

• comments
• casing
• parameter order
• whitespace

Miscellany:

• support wrapped arrays? mf6 no longer has a line length restriction?
• currently flopy allows comments at the end of lines, with no comment character — consider requiring end of line comments to start with e.g. "#"?