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Selecting multiple columns in a pandas dataframe
...).
df1 = df[['a', 'b']]
Alternatively, if it matters to index them numerically and not by their name (say your code should automatically do this without knowing the names of the first two columns) then you can do this instead:
df1 = df.iloc[:, 0:2] # Remember that Python does not slice inclusive of...
How do I override __getattr__ in Python without breaking the default behavior?
I want to override the __getattr__ method on a class to do something fancy but I don't want to break the default behavior.
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How do you trigger a block after a delay, like -performSelector:withObject:afterDelay:?
Is there a way to call a block with a primitive parameter after a delay, like using performSelector:withObject:afterDelay: but with an argument like int / double / float ?
...
关于 __VA_ARGS__ 宽字符版本的问题 - C/C++ - 清泛网 - 专注C/C++及内核技术
关于 __VA_ARGS__ 宽字符版本的问题在写一个可变参数的记录日志函数，考虑到宽字符（Unicode版本）时：#define WIDEN2(x) L ## x#define WIDEN(x) WIDEN2(x)#define __...在写一个可变参数的记录日志函数，考虑到宽字符（Unicode版本）时：
#defin...
Compile time string hashing
... string length, and the compiler is not clever enough to elide the second call. Check other answers for possible fix for this problem.
– CygnusX1
Feb 27 '16 at 16:34
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How to extract the year from a Python datetime object?
...ew times and you'll be prompted with the members of the "now" object:
now.__add__ now.__gt__ now.__radd__ now.__sub__ now.fromordinal now.microsecond now.second now.toordinal now.weekday
now.__class__ now.__hash__ ...
How to Detect if I'm Compiling Code with a particular Visual Studio version?
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_MSC_VER and possibly _MSC_FULL_VER is what you need. You can also examine visualc.hpp in any recent boost install for some usage examples.
Some values for the more recent versions of the compiler are:
MSVC++ 14.24 _MSC_VER...
Select distinct values from a table field
...ant any ordering to be applied to a query, not even the default ordering, call order_by() with no parameters.
and distinct() in the note where it discusses issues with using distinct() with ordering.
To query your DB, you just have to call:
models.Shop.objects.order_by().values('city').distinct(...
.gitignore all the .DS_Store files in every folder and subfolder
...k the problem you're having is that in some earlier commit, you've accidentally added .DS_Store files to the repository. Of course, once a file is tracked in your repository, it will continue to be tracked even if it matches an entry in an applicable .gitignore file.
You have to manually remove th...
UML class diagram enum
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They are simply showed like this:
_______________________
| <<enumeration>> |
| DaysOfTheWeek |
|_____________________|
| Sunday |
| Monday |
| Tuesday |
| ... |
|____________________...