Question

I’m looking for some advice on how to create a data structure by parsing a file.
This is the list i have in my file.

'01bpar( 2)=  0.23103878E-01  half_life=  0.3000133E+02  relax_time=  0.4328278E+02',
'01bpar( 3)=  0.00000000E+00',
'02epar( 1)=  0.49998963E+02',
'02epar( 2)=  0.23103878E-01  half_life=  0.3000133E+02  relax_time=  0.4328278E+02',
'02epar( 3)=  0.00000000E+00',
'02epar( 4)=  0.17862340E-01  half_life=  0.3880495E+02  relax_time=  0.5598371E+02',
'02bpar( 1)=  0.49998962E+02',
'02bpar( 2)=  0.23103878E-01  half_life=  0.3000133E+02  relax_time=  0.4328278E+02',

What I need to do is construct a data structure which chould look like this:

http://img11.imageshack.us/img11/7645/datastructure.gif

(couldn’t post it becouse of new user restriction)

I’ve managed to get all the regexp filters to get what is needed, but i fail to construct the structure.
Ideas?

Answer 1

Consider using a dict of dicts.

#!/usr/bin/env python
import re
import pprint
raw = """'01bpar( 2)=  0.23103878E-01  half_life=  0.3000133E+02  relax_time=  0.4328278E+02',
'01bpar( 3)=  0.00000000E+00',
'02epar( 1)=  0.49998963E+02',
'02epar( 2)=  0.23103878E-01  half_life=  0.3000133E+02  relax_time=  0.4328278E+02',
'02epar( 3)=  0.00000000E+00',
'02epar( 4)=  0.17862340E-01  half_life=  0.3880495E+02  relax_time=  0.5598371E+02',
'02bpar( 1)=  0.49998962E+02',
'02bpar( 2)=  0.23103878E-01  half_life=  0.3000133E+02  relax_time=  0.4328278E+02',"""

datastruct = {}
pattern = re.compile(r"""\D(?P<digits>\d+)(?P<field>[eb]par)[^=]+=\D+(?P<number>\d+\.\d+E[+-]\d+)""")
for line in raw.splitlines():
    result = pattern.search(line)
    parts = result.groupdict()
    if not parts['digits'] in datastruct:
        datastruct[parts['digits']] = {'epar':[], 'bpar':[]}
    datastruct[parts['digits']][parts['field']].append(parts['number'])

pprint.pprint(datastruct, depth=4)

Produces:

{'01': {'bpar': ['0.23103878E-01', '0.00000000E+00'], 'epar': []},
 '02': {'bpar': ['0.49998962E+02', '0.23103878E-01'],
        'epar': ['0.49998963E+02',
                 '0.23103878E-01',
                 '0.00000000E+00',
                 '0.17862340E-01']}}

Revised version in light of comments:

pattern = re.compile(r"""\D(?P<digits>\d+)(?P<field>[eb]par)[^=]+=\D+(?P<number>\d+\.\d+E[+-]\d+)""")

default = lambda : dict((('epar',[]), ('bpar',[])))
datastruct = defaultdict( default)

for line in raw.splitlines():
    result = pattern.search(line)
    parts = result.groupdict()
    datastruct[parts['digits']][parts['field']].append(parts['number'])

pprint.pprint(datastruct.items())

which produces:

[('02',
  {'bpar': ['0.49998962E+02', '0.23103878E-01'],
   'epar': ['0.49998963E+02',
            '0.23103878E-01',
            '0.00000000E+00',
            '0.17862340E-01']}),
 ('01', {'bpar': ['0.23103878E-01', '0.00000000E+00'], 'epar': []})]