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How to search in array of object in mongodb
...hout $elemMatch mongo will look for users with National Medal in some year and some award in 1975s, but not for users with National Medal in 1975.
See MongoDB $elemMatch Documentation for more info. See Read Operations Documentation for more information about querying documents with arrays.
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Is there a performance difference between a for loop and a for-each loop?
... The for-each loop, introduced in
release 1.5, gets rid of the clutter
and the opportunity for error by
hiding the iterator or index variable
completely. The resulting idiom
applies equally to collections and
arrays:
// The preferred idiom for iterating over collections and arrays
for (...
install / uninstall APKs programmatically (PackageManager vs Intents)
My application installs other applications, and it needs to keep track of what applications it has installed. Of course, this could be achieved by simply keeping a list of installed applications. But this should not be necessary! It should be the responsibility of the PackageManager to maintain the ...
How good is Java's UUID.randomUUID?
I know that randomized UUIDs have a very, very, very low probability for collision in theory, but I am wondering, in practice, how good Java's randomUUID() is in terms of not having collision? Does anybody have any experience to share?
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Accidentally committed .idea directory files into git
... filesystem
Send the change to others
Third, commit the .gitignore file and the removal of .idea from the repository. After that push it to the remote(s).
Summary
The full process would look like this:
$ echo '.idea' >> .gitignore
$ git rm -r --cached .idea
$ git add .gitignore
$ git com...
dplyr: “Error in n(): function should not be called directly”
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I presume you have dplyr and plyr loaded in the same session. dplyr is not plyr. ddply is not a function in the dplyr package.
Both dplyr and plyr have the functions summarise/summarize.
Look at the results of conflicts() to see masked objects.
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Is there a performance difference between i++ and ++i in C?
Is there a performance difference between i++ and ++i if the resulting value is not used?
14 Answers
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ImportError: No module named requests
...requests (or pip3 install requests for python3) if you have pip installed and Pip.exe added to the Path Environment Variable. If pip is installed but not in your path you can use python -m pip install requests (or python3 -m pip install requests for python3)
Alternatively from a cmd prompt, use &g...
In Django, how do I check if a user is in a certain group?
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then user.groups.all() returns [<Group: Editor>].
Alternatively, and more directly, you can check if a a user is in a group by:
if django_user.groups.filter(name = groupname).exists():
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Note that groupname can also be the actual Django Group object.
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Using Moq to determine if a method is called
It is my understanding that I can test that a method call will occur if I call a higher level method, i.e.:
3 Answers
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