Add a function to get ids before dataframe

[alkino]

Fix #149

[NadirRoGue]

Everything looks good

[sergiorg-hpc]

@mgeplf I asked @alkino to make some changes here in regards to the min,max and positions. Even though the code looks clear and simpler by duplicating the loop that goes through all the ids, this is a bit tricky, because some reports might have millions of cells and we would be wasting time by duplicating the loop and going through all the cells twice.

Thus, I suggested to try to keep the original design while still not affecting the performance of libsonata. A simple lambda parameter could be an option and, thus, the fun parameter that Nico added for illustration purposes.

[mgeplf]

I would like to get this merged before I do a libsonata release, but I'm still puzzled by the comments; can you have a look @alkino?

[alkino]

updated

[mgeplf]

I changed the name of the function, and tried to make the docstrings more clear. @NadirRoGue or @alkino could you clean them up further; things like getIds don't really convey what IDs are being retrieved. In addition, the format of the return would be helpful for things like getNodeIdElementIdMapping

[NadirRoGue]

I've added some extra doc for the return format of getNodeIdElementIdMapping, let me know if that's what you mean @mgeplf . For the rest, both the API and doc seems clear to me.

[mgeplf]

Ok, I'll take it from here, I guess. Thanks.