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Dynamically select data frame columns using $ and a character value

...and some variable names stored in a character vector cols . When I try to select a variable from mtcars using a dynamic subset of cols , nether of these work ...
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Using Chrome's Element Inspector in Print Preview Mode?

...versions). Check the Emulate print media checkbox at the Rendering tab and select the Print media type. Chrome v48+ (Thanks Alex for noticing): Open the Developer Tools (CTRLSHIFTI or F12) Click the Toggle device mode button in the left top corner (CTRLSHIFTM). Make sure the console is shown by c...
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How to install Xcode Command Line Tools

... Xcode 5.1 and OSX 10.9. (also works with Xcode 5.1.1 + OSX 10.10) xcode-select --install worked with version 2333, failed with version 2003. So, try xcode-select --install and if that does not work download as described below. In early February 2014 xcode-select --install has been reporting that...
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Print array elements on separate lines in Bash?

...ds to the args merged into one argument: "$1c$2c..." (where c is the first char of IFS). You almost always want "$@". Same goes for "${arr[@]}". Always quote them! share | improve this answer ...
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Why do you create a View in a database?

...e a View in their database? Why not just run a normal stored procedure or select? 25 Answers ...
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how to stop browser back button using javascript

...me because window.location.hash should always return the hash with the '#' character and _hash will never contains the '#' caracter. Do you recall anything on that ? Is that just a protection in case the browser does not return the '#' char in location.hash ? – baraber ...
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Delete branches in Bitbucket

... in Bitbucket go to branches in left hand side menu. Select your branch you want to delete. Go to action column, click on three dots (...) and select delete. share | improve t...
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How do I use itertools.groupby()?

...string)] will give you a list of 2-tuples where the first element is the char and the 2nd is the number of repetitions. Edit: Note that this is what separates itertools.groupby from the SQL GROUP BY semantics: itertools doesn't (and in general can't) sort the iterator in advance, so groups with t...
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How to list records with date from the last 10 days?

...date) Why don't you just try it? The standard ANSI SQL format would be: SELECT Table.date FROM Table WHERE date > current_date - interval '10' day; I prefer that format as it makes things easier to read (but it is the same as current_date - 10). ...
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Is there a standard for storing normalized phone numbers in a database?

... A good old nvarchar(42) with a bit of validation /^+?[0-9 -\.\(\)#*]{4,41}$/ works very well! – SandRock Apr 5 '12 at 20:19 ...