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What is copy-on-write?
I would like to know what copy-on-write is and what it is used for? The term 'copy-on-write array' is mentioned several times in the Sun JDK tutorials but I didn't understand what it meant.
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Understanding implicit in Scala
... of the reasons I stopped trying to learn Scala many years ago and am only now coming back to it. I was never sure where some (many) of the implicits were coming from in the code I was looking at.
– melston
Mar 19 '19 at 19:23
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How to generate Class Diagram (UML) on Android Studio (IntelliJ Idea)
...leUML jar from here https://plugins.jetbrains.com/plugin/4946-simpleumlce
Now follow the below steps.
Step 1:
Click on File and go to Settings (File → Settings)
Step 2
Select Plugins from Left Panel and click Install plugin from disk
Step 3:
Locate the SimpleUML jar file and select ...
Mercurial move changes to a new branch
...eans, revision 0 is the base on which you started to work on your feature. Now you want to have revisions 1-2 on a named branch, let's say my-feature. Update to revision 0 and create that branch:
$ hg up 0
$ hg branch my-feature
$ hg ci -m "start new branch my-feature"
The history now looks like ...
Adding a column to a data.frame
...1, 1 + cumsum(nonpos))
> classes
[1] 1 1 1 1 2 2 2 2 2 2 2 3 3 3 3
Now, we can attach it back onto our data frame with cbind (by using the class= syntax, we can give the column the class heading):
> data_w_classes <- cbind(data, class=classes)
And data_w_classes now contains the re...
How to check if variable is string with python 2 and 3 compatibility
... in Python 2 in the most generic manner,
isinstance(s, basestring)
will now also work for Python 3+.
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Get current time in milliseconds in Python?
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@ParallelUniverse: .utcnow() uses GetSystemTimeAsFileTime() on recent CPython on Windows. Wouldn't time.clock() call (QueryPerformanceCounter()) introduce more noise than it might reduce? See Precision is not the same as accuracy.
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How can I make a weak protocol reference in 'pure' Swift (without @objc)
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What's the correct way of doing weak delegates now in Swift? Apple documentation is not showing or declaring the delegate as weak in their example code: developer.apple.com/library/ios/documentation/swift/conceptual/…
– C0D3
Dec 1 ...
Setting default permissions for newly created files and sub-directories under a directory in Linux?
...er linux systems are configured with per-user groups by default.
I don't know of a way to force the permissions you want if the user's umask is too strong.
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Summarizing multiple columns with dplyr? [duplicate]
...x. I have a data frame with different variables and one grouping variable. Now I want to calculate the mean for each column within each group, using dplyr in R.
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