KeyError虽然肯定在词典中

Question

I have an index that contains this:

IRD\0.jpg [  4.64939594e-01   6.48846030e-02   2.00261129e-04       0.00000000e+00 0.00000000e+00  ...    7.34290807e-04   6.90233335e-02   2.02463999e-01]

but when called here:

for (k, hist) in index.items():
    # compute the distance between the two histograms
    # using the method and update the results dictionary
    d = method(index['IRD\0.jpg'], hist)
    results[k] = d

it comes up with this error:

KeyError Traceback (most recent call last)
<ipython-input-98-b7c782484164> in <module>()
# compute the distance between the two histograms
# using the method and update the results dictionary
d = method(index['IRD\0.jpg'], hist)
results[k] = d

and I don't really get why? Help would be highly appreciated and I'm sorry if I'm missing something obvious but I am fairly new to this :)

Answer 1

It's because \\ is the escape character in strings. If you want it to be interpreted as an actual char in the string, then you have to escape it:

>>> print('x\0')
x
>>> print('x\\0')
x\0

so change index['IRD\\0.jpg'] to index['IRD\\\\0.jpg']