大约有 47,000 项符合查询结果(耗时:0.0871秒) [XML]

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What is the difference between NaN and None?

I am reading two columns of a csv file using pandas readcsv() and then assigning the values to a dictionary. The columns contain strings of numbers and letters. Occasionally there are cases where a cell is empty. In my opinion, the value read to that dictionary entry should be None but instead ...
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There can be only one auto column

How do I correct the error from MySQL 'you can only have one auto increment column'. 4 Answers ...
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What does the “@” symbol do in Powershell?

I've seen the @ symbol used in PowerShell to initialise arrays. What exactly does the @ symbol denote and where can I read more about it? ...
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Using IoC for Unit Testing

How can a IoC Container be used for unit testing? Is it useful to manage mocks in a huge solution (50+ projects) using IoC? Any experiences? Any C# libraries that work well for using it in unit tests? ...
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Adding a build configuration in Xcode

I'd like to add a new build configuration in Xcode 5, "QA", to the other three we currently have (Debug, Distribution, Release). However, when I click "Editor > Add Configuration", everything is grayed out. I'm not very familiar with Xcode in the first place, so I'm not sure how to go about doing th...
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How to tell Maven to disregard SSL errors (and trusting all certs)?

I frequently need to run "mvn" command : 4 Answers 4 ...
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JUnit 4 Test Suites

How do I create test suites with JUnit 4? 5 Answers 5 ...
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How can I create an array with key value pairs?

How can I add key value pairs to an array? 6 Answers 6 ...
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What is the right way to override a setter method in Ruby on Rails?

I am using Ruby on Rails 3.2.2 and I would like to know if the following is a "proper"/"correct"/"sure" way to override a setter method for a my class attribute. ...
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Copying text to the clipboard using Java

I want to copy text from a JTable 's cell to the clipboard, making it available to be pasted into other programs such as Microsoft Word. I have the text from the JTable , but I am unsure how to copy it to the clipboard. ...