Create low level functions for mzTab-M export

[jorainer]

Evaluate if it would be possible to split the export functionality into individual, small, functions for each element of an mzTab-M file. These functions should take base R data types as input and write to a text file. Suggested function names:

• write_mtd()
• write_smh()
• write_sml()
• write_smf()
• ...

Functions are partially already implemented in MsIO, but need to be adapted to work with base data types as input.

[jorainer]

for devs: make PR from your changes/branches into the issue_35 branch.

[jorainer]

• Define and export MTD section. Goal is to have helper function that take e.g. a sample data.frame as input and then reformat that into the MTB sample/assay/run parts of the MTD section. Work in progress (PR feat: add helper function for the MTD CV entries #36)
  • general information: mtd_skeleton()
  • ms_run: mtd_ms_run()
  • sample information
  • assay information
  • study variable information
• Define and export SML section.
• Define and export SMF section.
• Define and export SME section.

[jorainer]

I finished now implementing all the metadata helper functions. An example usage (very rudimentary) is in the fist documentation entry in the MTD.R file

[philouail]

Very happy with the current state of the MTD export. I would like to continue with the SML which would allow use to have a minimal example of an mzTabM file and then we can both work on the implementation and validation.

[jorainer]

I will move the code from the respective branch to the new home mentioned in #38

[jorainer]

Closing this issue as the related development should happen in https://github.com/RforMassSpectrometry/RmzTabM