Eric Lemoine wrote:
> Yes, repr. It was in the provided code snippet. Thanks. Eric
yes, indeed it was. sorry about that.
I think that's a mistake. Python's repr() is designed to satisfy:
eval(repr(object)) == object
that can't always be done, but that's the theory -- it's a good way to
convert python objects into python code, but in this case, we're turning
python objects into JavaScript code.
In the case of floats, repr() returns a litteral that has enough digits
to guarantee the above. So, for instance, when you have start with a
value that can't be exactly represented as a float, you get a lot of digits:
>>> f = 0.1
>>> repr(f)
'0.10000000000000001'
If there is an exact mapping from binary to decimal, you get a cleaner
result:
>>> f = 0.128
>>> repr(f)
'0.128'
Anyway, I doubt that what you really want in JSON is that full number of
digits.
Options:
(1) Use str() instead. It gives a "clean" result, apparently truncating
to 12 significant figures. As a python float can hold up to 14 decimal
figures, that's pretty good.
(2) Use string formatting, with the %g formatter. This lets you specify
the number of significant figures you want to display:
def FLOAT_REPR(f, Precision=8):
format_str = "%%.%ig"%Precision
return format_str%f
I don't know if the geoJSON API has a place to specify precision of
numbers, but it might be nice.
Either of these would work for floats and decimals (and integers, and
numpy types, I think)
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
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