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The way to check a HDFS directory's size?
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Prior to 0.20.203, and officially deprecated in 2.6.0:
hadoop fs -dus [directory]
Since 0.20.203 (dead link) 1.0.4 and still compatible through 2.6.0:
hdfs dfs -du [-s] [-h] URI [URI …]
You can also run hadoop fs -help for more info and specifics...
How can I get a count of the total number of digits in a number?
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@Puterdo Borato: my performance test actually showed that your method is faster when the number of digits are < 5. Pass that, Steve's Math.floor is faster.
– stack247
Apr 7 '15 at 22:56
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How to check if multiple array keys exists
... check (like in the original question), it's probably easy enough to just call array_key_exists() twice to check if the keys exists.
if (array_key_exists("story", $arr) && array_key_exists("message", $arr)) {
// Both keys exist.
}
However this obviously doesn't scale up well to many k...
Why does ~True result in -2?
...00000001
and ~1 is:
11111110
Which is -2 in Two's complement1
1 Flip all the bits, add 1 to the resulting number and interpret the result as a binary representation of the magnitude and add a negative sign (since the number begins with 1):
11111110 → 00000001 → 00000010
↑ ...
Setting the filter to an OpenFileDialog to allow the typical image formats?
I have this code, how can I allow it to accept all typical image formats? PNG, JPEG, JPG, GIF?
11 Answers
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Difference between Observer, Pub/Sub, and Data Binding
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Here's my take on the three:
Data Binding
Essentially, at the core this just means "the value of property X on object Y is semantically bound to the value of property A on object B. No assumptions are made as to how Y knows or is fed changes on object B.
Observer, or Obser...
What is the behavior difference between return-path, reply-to and from?
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Now, let's describe the different "FROM"s.
The return path (sometimes called the reverse path, envelope sender, or envelope from — all of these terms can be used interchangeably) is the value used in the SMTP session in the MAIL FROM command. As you can see, this does not need to be the same v...
Truncate all tables in a MySQL database in one command?
Is there a query (command) to truncate all the tables in a database in one operation? I want to know if I can do this with one single query.
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Which iomanip manipulators are 'sticky'?
... the comments below:
By Martin:
@Chareles: Then by this requirement all manipulators are sticky. Except setw which seems to be reset after use.
By Charles:
Exactly! and the only reason that setw appears to behave differently is because there are requirements on formatted output operat...
Using -performSelector: vs. just calling the method
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Basically performSelector allows you to dynamically determine which selector to call a selector on the given object. In other words the selector need not be determined before runtime.
Thus even though these are equivalent:
[a...