Deepak Roy Chittajallu

We can use the [pandas dataframe](http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.html) for the features.

For boundaries, could we use a label map instead?

For label maps something like run-length encoding will save a lot of space since i would exprect these label maps to be quite sparse in number of non-zero valued pixels.

@cooperlab What kind of query operations would be doing mostly? - For classification problem usecases maybe we will need all nuclei in the slide or maybe in a specific region...

@renexu We are using CMake to build all cython code in the toolkit. Can you try this [fix](https://stackoverflow.com/questions/52502852/cmake-cant-find-stdc11-after-xcode-10-update)? I am on an old Xcode so i couldn't reproduce the error....

@jcfr Have you encountered this error in other scikit-build scenarios?

@joelive Thank you for reporting this. I will try to look into it. Could you please share a sample image to help with debugging?

It would be helpful to print the source and target types when that exception is raised for easy debugging

`No such validator string/string` is a good start. But as zach said it would be nice to know the id of the input/output which is causing this error. If there...

+1 for what zach suggests