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Express.js: how to get remote client address

...proxy server does not relay the information on where the request was originally. In this case, there would be no way to find out where the request was originally from. You need to modify configuration of the proxy server first. For example, if you use nginx as your reverse proxy, you may need to a...
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Converting strings to floats in a DataFrame

...newer version of pandas (0.17 and up), you can use to_numeric function. It allows you to convert the whole dataframe or just individual columns. It also gives you an ability to select how to treat stuff that can't be converted to numeric values: import pandas as pd s = pd.Series(['1.0', '2', -3]) p...
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Javascript - Track mouse position

I am hoping to track the position of the mouse cursor, periodically every t mseconds. So essentially, when a page loads - this tracker should start and for (say) every 100 ms, I should get the new value of posX and posY and print it out in the form. ...
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What does the unary plus operator do?

... It's there to be overloaded if you feel the need; for all predefined types it's essentially a no-op. The practical uses of a no-op unary arithmetic operator are pretty limited, and tend to relate to the consequences of using a value in an arithmetic expression, rather than the ...
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Why does sudo change the PATH?

... Yeah, but it's totally counterintuitive. It probably fools the good guys more than the bad guys. – Brian Armstrong Jun 20 '09 at 2:24 ...
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Pandas conditional creation of a series/dataframe column

... List comprehension is another way to create another column conditionally. If you are working with object dtypes in columns, like in your example, list comprehensions typically outperform most other methods. Example list comprehension: df['color'] = ['red' if x == 'Z' else 'green' for x in d...
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How do I remove all specific characters at the end of a string in PHP?

... using rtrim replaces all "." at the end, not just the last character $string = "something here.."; echo preg_replace("/\.$/","",$string); share | ...
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How to convert JSON string to array

...d keys). That's what the documentation says and that's what my PHP 5.2 installation returns. Are you using a function other than the official, built-in json_decode()? What does var_dump(json_decode($str, true)); return? – RickN Sep 22 '11 at 15:34 ...
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Can I start the iPhone simulator without “Build and Run”?

...u double-click it (or use the open terminal command), it will run. Incidentally, it's called "iOS Simulator.app" with newer iPhone SDKs. – Seth Mar 27 '12 at 22:58 1 ...
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When to use EntityManager.find() vs EntityManager.getReference() with JPA

... I usually use getReference method when i do not need to access database state (I mean getter method). Just to change state (I mean setter method). As you should know, getReference returns a proxy object which uses a powerful featu...