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How to check if a file is a valid image file?
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That won't be sufficient if he's really testing for "valid" images; the presence of a magic number doesn't guarantee that the file hasn't been truncated, for example.
– Ben Blank
May 20 '09 at 18:11
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Force R not to use exponential notation (e.g. e+10)?
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This is a bit of a grey area. You need to recall that R will always invoke a print method, and these print methods listen to some options. Including 'scipen' -- a penalty for scientific display. From help(options):
‘scipen’: integer. A penalty to be applied wh...
Entity Framework 6 Code first Default value
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You can do it by manually edit code first migration:
public override void Up()
{
AddColumn("dbo.Events", "Active", c => c.Boolean(nullable: false, defaultValue: true));
}
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MySQL get the date n days ago as a timestamp
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DATE_SUB will do part of it depending on what you want
mysql> SELECT DATE_SUB(NOW(), INTERVAL 30 day);
2009-06-07 21:55:09
mysql> SELECT TIMESTAMP(DATE_SUB(NOW(), INTERVAL 30 day));
2009-06-07 21:55:09
mysql> SELECT U...
How do I determine file encoding in OS X?
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That's a function call you would use if you want to write a program. From the command line, just type ls -l@ <filename> to see what attributes are set for the file. To see the actual attribute, type xattr -p com.apple.TextEncoding <fil...
jQuery OR Selector?
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It should be noted this isn't really an 'or' selector, more like multiple selectors in one.
– alex
Feb 15 '10 at 3:57
50
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If threads share the same PID, how can they be identified?
... +---------+
| process |
_| pid=42 |_
_/ | tgid=42 | \_ (new thread) _
_ (fork) _/ +---------+ \
/ +---------+
+---------+ | ...
Better way to sum a property value in an array
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Updated Answer
Due to all the downsides of adding a function to the Array prototype, I am updating this answer to provide an alternative that keeps the syntax similar to the syntax originally requested in the question.
class TravellerCollection e...
What is Scala's yield?
...I use yield instead of map? This map code is equivalent val res = args.map(_.toUpperCase) , right?
– Geo
Jun 27 '09 at 12:23
4
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Eclipse - no Java (JRE) / (JDK) … no virtual machine
... (the first one referenced by your PATH)
Three things to remember:
"Installing" a JRE or a JDK can be as simple as unzipping or copying it from another computer: there is no special installation steps, and you can have as many different JVM versions (1.4, 5.0, 6.0...) as you want, "installed" (co...