debug validator for ieeg (bep010): specification of HardwareFilters field in ieeg.json

[irisgroen]

I am having a difficult time figuring out how to format the HardwareFilter field for the visual_multimodal bids-example dataset (bids-standard/bids-examples#138) for the ieeg (bep010) branch. The following is not correct:

"HardwareFilters": "HighPass:0.16,LowPass:500",

I've have tried to add curly brackets to format according to these instructions:
https://github.com/bids-standard/bids-validator/blob/307b4b2e9aa6381c47e0b2f935b0bb081376f18c/validators/schemas/eeg.json#L29-L40

but the validator keeps throwing the following errors:
./sub-som682/ses-somecog01/ieeg/sub-som682_ses-somecog01_task-hrfpattern_run-01_ieeg.json
Evidence: .HardwareFilters should be object
./sub-som682/ses-somecog01/ieeg/sub-som682_ses-somecog01_task-hrfpattern_run-01_ieeg.json
Evidence: .HardwareFilters should match pattern "^n/a$"
./sub-som682/ses-somecog01/ieeg/sub-som682_ses-somecog01_task-hrfpattern_run-01_ieeg.json
Evidence: .HardwareFilters should match some schema in anyOf

Could someone please clarify? There are no examples in either bep006 or bep010 that actually have a hardware filters field in the eeg.json file as far as I could see. Thanks!

[sappelhoff]

you can find more information on how to define filters here: https://github.com/bids-standard/bids-starter-kit/wiki/FAQ#how-to-format-hardware-and-software-filter-fields-in-a-json

• A JSON object is content confined within curly brackets
• The content of a JSON object is a bunch of key-value pairs
• Keys are always strings such as "Key" or 'Key'
• Values can be anything, for example another JSON object

... defining the filters requires:

1. define an object
2. for each filter you want to define, add a new object

Your example:

{
"HighPass": {"cutoff": 0.16},
"LowPass": {"cutoff": 500}
}

Note that within a JSON object, you can define as many parameters as you want: not only the cutoff_frequency, but for example the filter slope (or other things).

Hope that helps!

[irisgroen]

That is indeed helpful, I get it now! I am writing the files using Matlab jsonwrite function and for some reason that added backward slashes in the name but when I manually removed those it passes the validator. Thanks @sappelhoff for your quick response!