Split an input string (substring)

[andrewc-moj]

I am quite new to ONNX but can see some real potential with it.

I'm building a custom graph for some simple transformations of data. For one in particular, I am trying to build an ONNX graph to parse (or subset) a string. For example, the string may be a date in the format yyyy-mm-dd and I would like to separate this single input into three separate outputs yyyy, mm and dd which I can then cast into an integer type to do some basic comparisons. I want to avoid operating on unix timestamp integers (representing dates) to ensure that my results match an existing model.

I have been scouring the internet and all the available operators to no avail. I'd be surprised if I was the the first to come across this, and would welcome any input. I wondered if slice or split could be applied to this kind of problem, but if i'm not mistaken, these separate arrays of inputs rather than single string input, but please let me know if i'm wrong!

As an aide aside, I thought the sklearn class CountVectorizer would probably implement some parsing of strings (build_tokenizer?) and I've also found a library called onnxruntime-extensions but perhaps reaching the limits of my knowledge.