help - iter & dict

[John Machin]

Something strange possessed Tim Chase and caused him to write:
> def findClosest(dataset, target):
[subtly *BUGGY* and overly verbose]

> def findClosest2(dataset, target):
[evil]

Try this (tested to the extent shown):

C:\junk>type dict_closest.py
def findClosest(dataset, target):
[snip]
def findClosest2(dataset, target):
[snip]

def findClosest3(dataset, target):
    closest_value = closest_key = closest_distance = None
    for k, v in dataset.items():
        distance = (target - v) ** 2
        # or use abs(target - v)
        if (closest_value is None
        or distance < closest_distance):
            closest_key = k
            closest_value = v
            closest_distance = distance
    return closest_key, closest_value

if __name__ == '__main__':
    for testno, test in enumerate([
        (4, {'a':1, 'b':3, 'c':6}),
        (0.1, {'a':0, 'b':3}),
        (0.1, {'a':3, 'b':0}),
        ]):
        target, data = test
        print
        for func in findClosest, findClosest2, findClosest3:
            k, v = func(data, target)
            print "test:%d func: %-13s -> %r %r" \
                % (testno + 1, func.__name__, k, v)
C:\junk>dict_closest.py

test:1 func: findClosest   -> 'b' 3
test:1 func: findClosest2  -> 'b' 3
test:1 func: findClosest3  -> 'b' 3

test:2 func: findClosest   -> 'b' 3 <<<<<<=======
test:2 func: findClosest2  -> 'a' 0
test:2 func: findClosest3  -> 'a' 0

test:3 func: findClosest   -> 'b' 0
test:3 func: findClosest2  -> 'b' 0
test:3 func: findClosest3  -> 'b' 0

HTH,
John