Lie Ryan wrote:
Steven D'Aprano wrote:
"If you’ve got the stomach for it, list comprehensions can be nested.
They are a powerful tool but – like all powerful tools – they need to be
used carefully, if at all."
How does this discourage the use of list comprehensions? At most, it
warns that complicated list comps are tricky. Complicated *anything*
are tricky.
and
"In real world, you should prefer builtin functions to complex flow
statements."
That's ridiculous. The example given is a special case. That's like
saying "Loops are hard, so in the real world, if you want a loop, find
a builtin function that does what you want instead."
What's the "builtin function" we're supposed to prefer over a "complex
flow statement" like this?
# split text into word fragments of length <= 3
sentence = "a sentence is a series of words"
new = [word[i:i+3] for word in sentence.split() for i in range(0,
len(word), 3)]
I often found list comprehension *more* readable than the equivalent
for-loop because of its density. Seeing complex for-loop requires one
step of thinking for each line, but in list comprehension I can skip
some of the steps because I know what list comprehension would roughly
look like.
i.e.
when I process this:
lst = [] #1
for i in range(10): #2
lst.append(i) #3
I do 3 steps of thinking for each line
but seeing this is only one step, since I know it is going to create new
list (skipping step #1) and I know i will be appended to that list
(skipping step #3)
I don't know what I was thinking before sending that last line, here is
what it was supposed to be:
but in list comprehension I see this in only one step, since I know it
is going to create new list (skipping step #1) and I know 'i' will be
appended to that list (skipping step #3) and this also continues to
nested list comprehensions
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