sorting items in a table problematic because of scientific notation
sjmachin at lexicon.net
Wed Apr 29 02:37:03 CEST 2009
Davis, Amelie Y <aydavis <at> purdue.edu> writes:
> Hi All,
> I have a
> dbf table outputted by another program that I cannot (I’m pretty sure)
> change the format of.
> I use a
> dbf reader code found online (http://code.activestate.com/recipes/362715/
> ) to read the table in and I need to sort it on a particular field but this
> field has scientific notation in it and when I use the following command, it
> seems to ignore the scientific notation which is very problematic outlist =
> sorted(records, key=itemgetter(2)) .
> I read
> through the help and it says to use ‘%f’ % to change the format but
> I’m not sure where to put that in the code (pasted below) as I think I’m
> not fully grasping the table structure...
> Here’s the data
> >>> db
> [['IN_FID', 'NEAR_FID',
> 'NEAR_DIST'], [('N', 9, 0), ('N', 9, 0), ('F', 19, 11)], [53, 55, '
The data type code for the offending column is "F" which is not in the
bog-standard dBase III set of C, N, D, and L. The code that you have used merely
returns unchanged the character string that finds in the data base.
> 1.05646365517e+005'], [53, 6, ' 9.32599134016e+004'], [53, 0, '
> 8.97477154418e+004'], [53, 2, ' 8.96449127749e+004'], [53, 1, '
> 7.88170078501e+004'], [53, 5, ' 8.29281503631e+004'], [53, 4, '
> è The
> ‘second item’ should be NEAR_ID = 64 but because of the scientific
> notation it returns NEAR_ID = 70.
> AND THE CODE
> # code from http://code.activestate.com/recipes/362715/
> if typ == "N":
> value = value.replace('\0', '').lstrip()
> if value == '':
> value = 0
> elif deci:
> value = decimal.Decimal(value)
> value = int(value)
> elif typ == 'D':
> y, m, d = int(value[:4]), int(value[4:6]),
> value = datetime.date(y, m, d)
> elif typ == 'L':
> value = (value in 'YyTt' and 'T') or (value
> in 'NnFf' and 'F') or '?'
raise Exception("Unknown data type " + typ)
> yield result
if this is a one-off exercise:
go with the post-processing fix that Skip gave you.
elif you are interested in a module that cares, is chock-full of assertions,
supports several more data type codes (including F) and memo fields (of 3
different varieties), and is not slower:
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