The the "Logical Error" question, this was brought up:
The big problem is this:
fullPath += [line.decode('utf-8', 'ignore').strip()]
which is an O(N**2) algorithm. Do you know that terminology? Very
briefly: O(1) means approximately constant time: tripling the size of
the input makes no difference to the processing time. O(N) means linear
time: tripling the input triples the processing time. O(N**2) means
quadratic time: tripling the input increases the processing time not by
a factor of three, but a factor of three squared, or nine.
With small files, and fast computers, you won't notice. But with huge
files and a slow computer, that could be painful.
Instead, a better approach is:
fullPath.append(line.decode('utf-8', 'ignore').strip())
which avoids the O(N**2) performance trap.
I have two questions:
1. How do you know that fullPath += [line.decode('utf-8', 'ignore').strip()] is
an O(N**2)?
2. How do you know that fullPath.append(line.decode('utf-8', 'ignore').strip())
is not?
--
David Rock
da...@graniteweb.com
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