getIndexDigit and getReservedBits #1024
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| ```py | ||
| h3.get_index_digit(h, digit) | ||
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| ```go | ||
| cell.IndexDigit(digit) | ||
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| ```sql | ||
| h3_get_index_digit(h, digit) | ||
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Are we sure we want to add these to the docs before they're actually implemented in the bindings?
| int H3_EXPORT(getReservedBits)(H3Index h) { return H3_GET_RESERVED_BITS(h); } | ||
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| /** | ||
| * Returns the index digits at `digit`, which starts with 1 for resolution |
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I would use "resolution" here to specify the function input, and "digit" as the fu 8000 nction output. I think that's more in line with how we use resolution elsewhere.
From the docs:
This is followed by a sequence of r digits 0-6, where each ith digit di specifies one of the 7 cells
centered on the cell indicated by the coarser resolution digits d1 through di-1. A local hexagon
coordinate system is assigned to each of the resolution 0 base cells and is used to orient all
hierarchical indexing child cells of that base cell. The assignment of digits 0-6 at each resolution
uses a Central Place Indexing arrangement (see [Sahr, 2014](http://webpages.sou.edu/~sahrk/sqspc/pubs/autocarto14.pdf))
But maybe that's just me. What do others think?
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Generally, a variable named res or resolution indicates to the user that it is an integer taking values 0--15. (In this case, its a little more restrictive at 1--15.) And digit indicates something taking values 0--6 (or 7 to indicate an invalid digit). I'd keep that same convention here.
Elsewhere in the codebase, we use res as the second argument to the H3_GET_INDEX_DIGIT macro, like here:
Line 227 in 73cf911
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As does the macro definition:
h3/src/h3lib/include/h3Index.h
Line 140 in 73cf911
#1022
This adds functions for retrieving index digits and the reserved bits from indexes. The reserved bits may be of interest for directedEdge / vertex mode where knowing which one it is are helpful.
Note that I chose to allow getIndexDigit to read unused digits; we could instead choose to disallow reading those digits from this function as they (probably) shouldn't be used as three-wide bit fields in that case.
Does not have CLI tests just yet.