On Mon, Apr 24, 2017 at 4:06 PM, Aldcroft, Thomas <aldcroft@head.cfa.harvard.edu> wrote:
>
> On Mon, Apr 24, 2017 at 4:06 PM, Robert Kern <robert.kern@gmail.com> wrote:
>>
>> I am not unfamiliar with this problem. I still work with files that have fields that are supposed to be in EBCDIC but actually contain text in ASCII, UTF-8 (if I'm lucky) or any of a variety of East European 8-bit encodings. In that experience, I have found that just treating the data as latin-1 unconditionally is not a pragmatic solution. It's really easy to implement, and you do get a program that runs without raising an exception (at the I/O boundary at least), but you don't often get a program that really runs correctly or treats the data properly.
>>
>> Can you walk us through the problems that you are having with working with these columns as arrays of `bytes`?
>
> This is very simple and obvious but I will state for the record.
I appreciate it. What is obvious to you is not obvious to me.
> Reading an HDF5 file with character data currently gives arrays of `bytes` [1]. In Py3 this cannot be compared to a string literal, and comparing to (or assigning from) explicit byte strings everywhere in the code quickly spins out of control. This generally forces one to convert the data to `U` type and incur the 4x memory bloat.
>
> In [22]: dat = np.array(['yes', 'no'], dtype='S3')
>
> In [23]: dat == 'yes' # FAIL (but works just fine in Py2)
> Out[23]: False
>
> In [24]: dat == b'yes' # Right answer but not practical
> Out[24]: array([ True, False], dtype=bool)
I'm curious why you think this is not practical. It seems like a very practical solution to me.
--
Robert Kern