[EMAIL PROTECTED] wrote:
> Im trying to iterate through values in a dictionary so i can find the
> closest value and then extract the key for that value....what ive done so far:
[snip]
> short time. I was trying to define a function (its my first!) so that i
> could apply to several 'dictionary's and 'exvalue's.
[snip]
If you plan on searching a single dictionary for many values, it may be
much faster to convert the dictionary into a sorted list, and use the
bisect module to find the closest value...
something like:
import bisect
class closer_finder:
def __init__(self, dataset):
self.dataset = dataset
flat = [(k,v) for v,k in dataset.iteritems()]
flat.sort()
self.flat = flat
def __getitem__(self, target):
flat = self.flat
index = bisect.bisect_right(flat, (target, ))
#simple cases, smaller than the smaller,
#or larger than the largest
if index == 0:
v,k = flat[0]
return k,v
elif index == len(flat):
v,k = flat[-1]
return k,v
#otherwise see which of the neighbors is closest.
leftval, leftkey = flat[index-1]
rightval, rightkey = flat[index]
leftdiff = abs(leftval - target)
rightdiff = abs(rightval - target)
if leftdiff <= rightdiff:
return leftkey, leftval
else:
return rightkey, rightval
In [158]:sample_data
Out[158]:{'a': 1, 'c': 6, 'b': 3}
In [159]:d=closer_finder(sample_data)
In [160]:d.flat
Out[160]:[(1, 'a'), (3, 'b'), (6, 'c')]
In [161]:d[4]
Out[161]:('b', 3)
--
- Justin
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