Stuck with Number Float format in Python Decimal

Question

I am working on a code and there I get data in the form of :

k=[{'item_id': '43381702', 'length': {'_exp': -2, '_is_special': False, '_int': '0', '_sign': 0}, 'height': {'_exp': -2, '_is_special': False, '_int': '0', '_sign': 0}, 'width': {'_exp': -2, '_is_special': False, '_int': '0', '_sign': 0}, 'unitweight': {'_exp': -3, '_is_special': False, '_int': '3000', '_sign': 0}, 'quantity': 1}]

And It is expected that when I write

float(k[0]['unitweight'])

It should be converted into a float number . But It is giving

TypeError: float() argument must be a string or a number

as expected. I am confused as the data is of the same form as is implemented inside python Decimal Module. Is there any way (one-liner) By which I can convert the data in float ?

This link has the same question probably . Check out this also .

I think It is the attribute of a number. Check out [tip](http://www.itmaybeahack.com/homepage/books/nonprog/html/p13_modules/p13_c03_decimal.html#rounding-known-as-quantization) about attribue error and this [link](http://mail.python.org/pipermail/python-checkins/2007-November/063656.html) also which shows the modification in python's code . — tusharmakkar08, May 31 '13 at 06:42

Mike Müller · Accepted Answer · 2013-05-31T07:00:16.927

2

Taking this:

d = {'_exp': -3, '_is_special': False, '_int': '3000', '_sign': 0}

for:

k[0]['unitweight']

You could do something like this:

import math  
math.copysign(int(d['_int']) ** d['_exp'], d['_sign'] * -1)

Result:

3.7037037037037036e-11

No idea what '_is_special' means.

edited May 31 '13 at 07:00

answered May 31 '13 at 06:33

Mike Müller

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+1 except your copy sign is wrong since the values are either `0` or `1` – jamylak May 31 '13 at 06:40
And what is plus and what is minus? 0: plus, 1: minus? – Mike Müller May 31 '13 at 06:52
`1` means sign is set, so negative, and `0` means it isn't, so positive. You could just use `-2*sign + 1` to get `1` or `-1` depending on the sign. Or something more readable like `-1 if sign else 1` – jamylak May 31 '13 at 06:55
Thanks. Just figured it out myself be looking at `decimal.Decimal`. And modified the solution. – Mike Müller May 31 '13 at 06:57
Is there any inbuilt function defined for this conversion ? Or I need to code out the stuff as @MikeMüller did . – tusharmakkar08 May 31 '13 at 07:01

Stuck with Number Float format in Python Decimal

1 Answers1