Virgil Stokes wrote:
>>> def testFunc(startingList):
>>>xOnlyList = []; j = -1
>>>for xl in startingList:
>>>if (xl[0] == 'x'):
>> That's going to fail in the starting list contains an empty string. Use
>> xl.startswith('x') instead.
> Yes, but this was by design (tacitly assumed that startingList was both a
> list and non-empty).
You missunderstood it will fail if the list contains an empty string, not if
the list itself is empty:
>>> words = ["alpha", "", "xgamma"]
>>> [word for word in words if word[0] == "x"]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: string index out of range
The startswith() version:
>>> [word for word in words if word.startswith("x")]
['xgamma']
Also possible:
>>> [word for word in words if word[:1] == "x"]
['xgamma']
> def testFunc1(startingList):
> '''
> Algorithm-1
> Note:
> One should check for an empty startingList before
> calling testFunc1 -- If this possibility exists!
> '''
> return([x for x in startingList if x[0] == 'x'],
> [x for x in startingList if x[0] != 'x'])
>
>
> I would be interested in seeing code that is faster than algorithm-1
In pure Python? Perhaps the messy variant:
def test_func(words):
nox = []
append = nox.append
withx = [x for x in words if x[0] == 'x' or append(x)]
return withx, nox
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