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Reverse a string in Python
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How about:
>>> 'hello world'[::-1]
'dlrow olleh'
This is extended slice syntax. It works by doing [begin:end:step] - by leaving begin and end off and specifying a step of -1, it reverses a string.
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Can hash tables really be O(1)?
It seems to be common knowledge that hash tables can achieve O(1), but that has never made sense to me. Can someone please explain it? Here are two situations that come to mind:
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Lambda function in list comprehensions
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271
The first one creates a single lambda function and calls it ten times.
The second one doesn't ca...
Get the index of the nth occurrence of a string?
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10 Answers
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How to create NS_OPTIONS-style bitmask enumerations in Swift?
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15 Answers
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Best way to find if an item is in a JavaScript array? [duplicate]
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As of ECMAScript 2016 you can use includes()
arr.includes(obj);
If you want to support IE or other older browsers:
function include(arr,obj) {
return (arr.indexOf(obj) != -1);
}
EDIT:
This will not work on IE6, 7 or 8 though. The bes...
pandas dataframe columns scaling with sklearn
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221
I am not sure if previous versions of pandas prevented this but now the following snippet works ...
How to extract the decision rules from scikit-learn decision-tree?
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