On 10/27/11 7:51 PM, Travis Oliphant wrote: > As I mentioned. I find the ability to separate an ABSENT idea from an > IGNORED idea convincing. In other words, I think distinguishing between > masks and bit-patterns is not just an implementation detail, but > provides a useful concept for multiple use-cases.
Exactly -- while one can implement ABSENT with a mask, one can not implement IGNORE with a bit-pattern. So it is not an implementation detail. I also think bit-patterns are a bit of a dead end: - there is only a standard for one data type family: i.e. NaN for ieee float types - So we would be coming up with our own standard (or adopting an existing one, but I don't think there is one widely supported) for other types. This means: 1) a lot of work to do 2) a binary format incompatible with other code, compilers, etc. This is a BIG deal -- a major strength of numpy is that it serves as a wrapper for a data block that is compatible with C, Fortran or whatever code -- special bit patterns would make this a lot harder. We also talked about the fact that a 8-bit mask provides the ability to carry other information in the mask -- not jsut "missing" or "ignored", but a handful of other possible reasons for masking. I think that has a lot of possibilities. On 10/28/11 2:11 AM, Stéfan van der Walt wrote: > Another data point: I've been spending some time on scikits-image > recently, and although masked values would be highly useful in that > context, the cost of doubling memory use (for uint8 images, e.g.) is > too high. > 2) that we make a concerted effort to implement the bitmask mode of > operation as soon as possible. I wonder if that might be handled as a scikits-image extension, rather than core numpy? Is there a standard bit pattern for missing data in images? -- it's presumable quite important to maintain binary compatibility with image formats, processing tools, etc. I guess what I'm getting at is that special bit-pattern implementations may be domain specific. -Chris -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception chris.bar...@noaa.gov _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion