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Is it possible to use 'else' in a list comprehension? [duplicate]
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The syntax a if b else c is a ternary operator in Python that evaluates to a if the condition b is true - otherwise, it evaluates to c. It can be used in comprehension statements:
>>> [a if a else 2 for a in [0,1,0,3]]
[2, 1, 2,...
Check if two unordered lists are equal [duplicate]
I'm looking for an easy (and quick) way to determine if two unordered lists contain the same elements:
8 Answers
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What is the difference among col-lg-*, col-md-* and col-sm-* in Bootstrap?
What is the difference among col-lg-* , col-md-* and col-sm-* in Twitter Bootstrap?
11 Answers
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How do I check if a string is unicode or ascii?
...You can tell which using code something like this:
def whatisthis(s):
if isinstance(s, str):
print "ordinary string"
elif isinstance(s, unicode):
print "unicode string"
else:
print "not a string"
This does not distinguish "Unicode or ASCII"; it only distinguish...
Remove all the elements that occur in one list from another
...es exactly what you want and stores the result in l3:
l3 = [x for x in l1 if x not in l2]
l3 will contain [1, 6].
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Replace values in list using Python [duplicate]
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Build a new list with a list comprehension:
new_items = [x if x % 2 else None for x in items]
You can modify the original list in-place if you want, but it doesn't actually save time:
items = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
for index, item in enumerate(items):
if not (item ...
How to create the most compact mapping n → isprime(n) up to a limit N?
...the primality test.
There isn't really a data structure for you to query. If you have lots of numbers to test, you should probably run a probabilistic test since those are faster, and then follow it up with a deterministic test to make sure the number is prime.
You should know that the math behind...
Why can't R's ifelse statements return vectors?
I've found R's ifelse statements to be pretty handy from time to time. For example:
9 Answers
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Why are these numbers not equal?
...equal function. Or rather, since all.equal gives lots of detail about the differences if there are any, isTRUE(all.equal(...)).
if(isTRUE(all.equal(i,0.15))) cat("i equals 0.15") else cat("i does not equal 0.15")
yields
i equals 0.15
Some more examples of using all.equal instead of == (the las...
Split List into Sublists with LINQ
...By(x=>f(x)).First() will never yield a group. OP asked about lists, but if we write to work with IEnumerable, making only a single iteration, we reap the performance advantage.
– Colonel Panic
Jul 11 '12 at 22:16
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