building lists of dictionaries

[Ernesto García García]

>>parinfo = [{'value':0., 'fixed':0, 'limited':[0,0],
>>'limits':[0.,0.]}.copy() for i in xrange(0,6)]
>>
>>However, this will still reference internal lists that have
>>been referenced multiple times, such that
>>
>> >>> parinfo[5]['limited']
>>[0, 0]
>> >>> parinfo[4]['limited'][0] = 2
>> >>> parinfo[5]['limited']
>>[2, 0]
> 
> Interesting. Cut-and-paste to my python prompt and I get
> 
>>>>parinfo[5]['limited']
> 
> [0, 0]
> 
> Tried both Python 2.4.1 and 2.5 beta, Linux, GCC 4.0.2

Of course. The expression within the list comprehension is evaluated for 
each iteration, so that the objects are recreated each time. The copy() 
for the dictionary is also not needed:

 >>> parinfo = [{'value':0., 'fixed':0, 'limited':[0,0], 
'limits':[0.,0.]} for i in xrange(0,6)]
 >>> parinfo
[{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}, 
{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}, 
{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}, 
{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}, 
{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}, 
{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}]
 >>> parinfo[0]['limited']
[0, 0]
 >>> parinfo[0]['limited'][0]=1
 >>> parinfo
[{'limited': [1, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}, 
{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}, 
{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}, 
{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}, 
{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}, 
{'limited': [0, 0], 'fixed': 0, 'limits': [0.0, 0.0], 'value': 0.0}]

Ernesto