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Error in if/while (condition) {: missing Value where TRUE/FALSE needed

...pen accidentally as the results of calculations: if(TRUE && sqrt(-1)) {} ## Error in if (TRUE && sqrt(-1)) { : missing value where TRUE/FALSE needed To test whether an object is missing use is.na(x) rather than x == NA. See also the related errors: Error in if/while (conditi...
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Why don't :before and :after pseudo elements work with `img` elements? [duplicate]

... 128 The spec says... Note. This specification does not fully define the interaction of :before...
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Where can I download Jai and Jai-imageio? [closed]

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F12 Jump to method -> go back to previous method after making the jump?

I can jump to code if I click in a method name and hit F12. But, is there a keyboard short cut to jump back to the previous code editor location? ...
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Format number as fixed width, with leading zeros [duplicate]

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UIWebView background is set to Clear Color, but it is not transparent

... 361 Also set : [webView setBackgroundColor:[UIColor clearColor]]; [webView setOpaque:NO]; ...
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Rails - link_to helper with data-* attribute [duplicate]

... 219 Just pass them in... Rails has a default :data hash = link_to body, url, :data => { :foo =&...
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How do I fetch a branch on someone else's fork on GitHub? [duplicate]

... 261 $ git remote add theirusername git@github.com:theirusername/reponame.git $ git fetch theiruserna...
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How to change a string into uppercase

... 1258 >>> s = 'sdsd' >>> s.upper() 'SDSD' See String Methods. ...
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sed fails with “unknown option to `s'” error [closed]

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