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Filling unwritten/invalid regions, e.g., access outside of written
ADIOS blocks, with not-a-number (NaN) created some confusion.
Technically, data in this region is literally not-a-number (yet), but
it seems easier to process data when it is just filled with zeros
instead.
We now always fill with zeros, hoping that "why is a region empty"
("because it was not written") does not create another kind of
confusion.
Side note: resizing during write of BTD is non-trivial (as in:
not supported by HDF5 and ADIOS), because we need to resize from
the "lower index end". HDF5 and ADIOS only support resizing the
upper index bound.
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Preferred solution for BTD: Might require an extra openPMD meta-data attribute to track. |
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Filling unwritten/invalid regions, e.g., access outside of written ADIOS blocks, with not-a-number (NaN) created some confusion: BLAST-WarpX/warpx#4775
Counter-point to this PR:
Technically, data in this region is literally not-a-number (yet). Matplotlib gracefully ignores NaNs for plotting, and can be configured to mask one way or the other with color. Padding with zeros is ambiguous: maybe data was not written, maybe data was written and truly zero.
We now always fill with zeros, hoping that "why is a region empty" ("because it was not written") does not create another kind of confusion.
Side note: resizing during write of BTD is non-trivial (as in: not supported by HDF5 and ADIOS), because we need to resize from the "lower index end". HDF5 and ADIOS only support resizing the upper index bound.
X-ref: #334 #340