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How to create NS_OPTIONS-style bitmask enumerations in Swift?
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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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'Must Override a Superclass Method' Errors after importing a project into Eclipse
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In a javascript array, how do I get the last 5 elements, excluding the first element?
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You can call:
arr.slice(Math.max(arr.length - 5, 1))
If you don't want to exclude the first element, use
arr.slice(Math.max(arr.length - 5, 0))
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Replacement for “rename” in dplyr
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dplyr version 0.3 added a new rename() function that works just like plyr::rename().
df <-...
把数据保存成 CSV 文件并分享出去 · App Inventor 2 中文网
...钮_记一笔、按钮_导出、按钮_导入，再拖一个标签 标签1 显示状态。
拖四个非可视组件：微数据库、文件管理器、信息分享器（在「社交应用」里）、计时器。文件管理器和计时器的属性都不用改。
实验一：先把数...
Changing the “tick frequency” on x or y axis in matplotlib?
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How to extract the decision rules from scikit-learn decision-tree?
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