support for export to cobrapy-compatible yaml format

[edkerk]

RAVEN should support writing a cobrapy-compatible yaml format, as this format is very concise.

• make writeYaml function that writes a text file, and parses through the model structure.
• remove old Yaml-export functionality
• modify exportForGit to support new writeYaml function
• confirm that output from this function is identical to cobrapy-yaml (except for RAVEN-unique fields)

A few considerations:

• Use the correct format. This example is old, rather use this example of the yeast consensus network.
• Do not reformat any ids to replace non-standard characters. This is done when writing SBML, as SBML doesn't support certain characters. But the YAML file should represent the model as it is in MATLAB.
• Include as many annotations as possible:

For each metabolite, include:

• mets
• metNames
• metComps
• inchis
• metFormulas
• metMiriams (any)
• metCharges
• unconstrained
• rxnFrom (?)

For each reaction, include:

• rxns
• rxnNames
• rxnComps
• metabolites and their stoichiometry
• grRules
• subSystems
• eccodes
• rxnMiriams (any)
• rxnNotes
• rxnConfidenceScores

For each compartment, include:

• comps
• compNames
• compOutside
• compMiriams

For each gene, include:

• genes
• geneComps
• geneMiriams
• geneShortNames

But of course only write those fields if they are present in the model.

[edkerk]

Another consideration. If you look at the example from yeast consensus network, metabolite names are appended with [compartment] in the cobrapy-version. This should not be done in this function, as it should represent how the model is presented in MATLAB.

[BenjaSanchez]

@edkerk sounds good! I will write the writeYaml function. I assume we should continue the work on branch fix/export_functions?

[edkerk]

Yups, I'll push devel to it, to ensure latest changes. (done: #80)

[edkerk]

A writeYaml function has been added in branch fix/export_functions: 23bb1f7

@BenjaSanchez a few points:

• note where publications are stored: pubmed ids can be stored in rxnMiriams (as pmid), while non-pubmed ids can be stored in rxnReferences. Neither should be stored in rxnNotes, this field is for generic notes

• note that not all fields are compulsory: if a model has rxnMiriams field, the function requires that is also has ec-codes, rxnKEGG and rxnNotes, according to line 110: if ~isempty(model.eccodes{pos}) || ~isempty(model.rxnKEGG{pos}) || ~isempty(model.rxnNotes{pos}) fails if one of them doesn't exist.

[BenjaSanchez]

@edkerk RE the first point, this is because I was using a COBRA structure, which does not support rxnMiriams, it can only store pmids either in rxnReferences or rxnNotes (see here), and at the moment they are stored in rxnNotes which get transfered to the same field by ravenCobraWrapper. Should I move those fields in the yeast model then to rxnReferences? In the case of a generic RAVEN model, there will not be any issue once we implement the generic extractMiriam we discussed in Gitter.

RE the second point, that I can also address once we have the improved extractMiriam

[edkerk]

1. Looking at the specification of Cobra model that you linked, they also indeed be in rxnReferences, for both Cobra and Raven. Also, there it specifies that rxnReferences is "Column Cell Array of Strings" and "of references for each corresponding reaction.", so not necessarily pubmed IDs.

2. You're right, an improved extractMiriam will probably change the code a bit anyway.

[edkerk]

Irrespective, pubmed IDs don't need to be prefixed with pmid:. This is done for ChEBI as it really is part of the identifier (here, CHEBI:17234), not because it would otherwise be a number-only. Also compare for instances ChEBI and KEGG compound on identifiers.org, pay attention to the identifier pattern.

[BenjaSanchez]

actually now testing with COBRA not even rxnReferences can be used to store things, as after a I/O cycle everything there gets transfered to rxnNotes. So pmid's will continue to be stored in the yeast model in rxnNotes with the format pmid:XXX; pmid:YYY, and I will include in ravenCobraWrapper a section for detecting these cases and sending them to rxnMiriams

[edkerk]

Perhaps then also start an issue at Cobra, because they do state that rxnReferences and rxnNotes are separate fields?

[tpfau]

@BenjaSanchez

actually now testing with COBRA not even rxnReferences can be used to store things, as after a I/O cycle everything there gets transfered to rxnNotes. So pmid's will continue to be stored in the yeast model in rxnNoteswith the format pmid:XXX; pmid:YYY, and I will include in ravenCobraWrappera section for detecting these cases and sending them to rxnMiriams

Could you give me an example for this in the COBRA toolbox?
In general: PMIDs should (imo) be added via MIRIAM annotations. Pubmed is listed on registry.org and is parsed by the COBRA toolbox SBML parser into the rxnReferences field, if it is correctly annotated (i.e. using the isDescribedBy bioql qualifier).
We try to put into notes things that are either invalid IDs (as mentioned above, PMID1234 is not a valid Pubmed id, while 1234 is, so if an invalid PMID is provided, that is likely to go into the notes field, but not into rxnReferences during IO cycles.

[BenjaSanchez]

@tpfau thanks for that insight! now with only the id the field gets properly stored in rxnReferences in a full cycle I/O. I've adapted the corresponding ravenCobraWrapper in RAVEN (df918f5) and the yeast model .xml (68d5e8a).