How to pre-read data size before downloading?(API selective download)

Hannah Ji
  • 2 Nov '18

First, thank you for your previous help. It really helped a lot!

I want to download Illustris-1 snapshot data, but only some of it.
Before downloading the data, I'd like to read the data size in order to check if my computer can afford it.
How can I?

Hannah Ji
  • 3
  • 2 Nov '18

And plus, I calculated stellar angular momentum of the first subhalo from snapshot data(mass, coordinates, velocites of PartType4, after excluding wind cells),
but the direction is very different from what is given in Angular_momentum.hdf5. (Almost 90 degree)
Is there something I missed?

Dylan Nelson
  • 5 Nov '18

Hi Hannah,

Do you mean, download snapshot files but only certain fields? The best way to anticipate the size, is just to roughly calculate it ahead of time. I.e.

size_GB = num_particles * (num_fields_float * 4 + num_fields_double * 8) / 1024**3 where most fields will be float (4 bytes), and only some (e.g. IDs, Coordinates, ...) will be double (8 bytes).

Hannah Ji
  • 6 Nov '18

Thank you!

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