Filter row fields if all rows are missing a value


is there a way to filter row fields themselves instead of just rows? We use multiple annotators to annotate variants and some of the fields that they return contain Nan for all the variants.

We would like to at least get a list of such row fields, but I did not find a way to do so, no matter which approach I tried it did not work (since our row fields have various types from integers to arrays of nested structs) or I run into stackoverflow error or out of memory. We always have only one sample, so one column, in a MatrixTable.

Thank you for any help!