Hehe, yeah I get that.
I guess that the expectation given the layout of print is that you see the first/last three columns, and first/last three rows, whereas the rows are a semi-arbitrary snapshot of the data rather than the extremes.
That code is super handy for pulling out zeros, but there may be NANs in the extremes or some other numerical aberration at “the end” of the data. I get that JSON doesn’t keep track of that, but I would have presumed that there was some other index for the order in which items were played into the fluid.dataset~ in the first place (which I understand may also not be in numerical order).
Even if the data structure can’t be preserved as such, perhaps the print command could go a step further and include a more robust numerical sorting for display purposes (e.g. 1, 2, 3…9, 10, 11, apples, bananas, carrots, etc…). Since the print command is (presumably) only used every now and then, even if that kind of sorting isn’t fast, it wouldn’t really matter much.