"Emin" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> On Jan 11, 5:53 pm, Steve Holden <[EMAIL PROTECTED]> wrote:
>>
>> What technique were you thinking of to look up the cached index values
>> in Python, just as a matter of curiosity? Storing them in a dict? It
>> would be hard to think of a faster way ... ;-)
>
> I didn't have anything fancy in mind. I was just wondering whether it
> makes sense to replace a block of code like
>
> data = {'a' : 1, 'b' :2, 'c' : 3}
> for i in someLargeList:
> for name in ['a','b','c']:
> result.append(data[name])
>
> with somthing like
>
> data = {'a' : 1, 'b' :2, 'c' : 3}
> dataValues = [data[k] for k in ['a','b','c']
> for i in someLargeList:
> for index in [0,1,2]:
> result.append(dataValues[index])
>
[Your as-posted code doesn't run, you are missing a trailing ']' in your
list comprehension. ]
So what you want is this?
1. Get the values from the data dict in order of their key, ['a','b','c']
(which is not the same as getting the data.values() list, which is in
unpredictable order)
2. For every element in some larger list, append each of the elements in
order from step 1 to some other result list.
First of all, realize that:
> for index in [0,1,2]:
> result.append(dataValues[index])
is the same as
result.extend(dataValues)
assuming that dataValues has exactly 3 elements in it.
Second, why are you iterating over someLargeList? You are doing nothing
with i, and neither the data dict nor the dataValues list changes as you
iterate.
This will do the job more quickly, I should think:
data = {'a' : 1, 'b' :2, 'c' : 3}
dataValues = [data[k] for k in ['a','b','c']]
result.extend( dataValues * len(someLargeList) )
-- Paul
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