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Mongodb Explain for Aggregation framework
...ther manipulation will be in-memory (possibly using temporary files if the allowDiskUse option is set).
Optimizing pipelines
In general, you can optimize aggregation pipelines by:
Starting a pipeline with a $match stage to restrict processing to relevant documents.
Ensuring the initial $match / ...
Mocking python function based on input arguments
...f side_effect is a function then whatever that function returns is
what calls to the mock return. The side_effect function is called with
the same arguments as the mock. This allows you to vary the return
value of the call dynamically, based on the input:
>>> def side_effect(value):
...
What should main() return in C and C++?
...d termination) according to the C++ standard. For C, re-entering main() is allowed, but should be avoided.
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Comparing two dataframes and getting the differences
...df2, works only for dataframes with identical rows and columns. In fact, all dataframes axes are compared with _indexed_same method, and exception is raised if differences found, even in columns/indices order.
If I got you right, you want not to find changes, but symmetric difference. For that, o...
How to escape single quotes within single quoted strings
...
If you really want to use single quotes in the outermost layer, remember that you can glue both kinds of quotation. Example:
alias rxvt='urxvt -fg '"'"'#111111'"'"' -bg '"'"'#111111'"'"
# ^^^^^ ^^^^^ ^...
How to set a Django model field's default value to a function call / callable (e.g., a date relative
... to create a field in the class.
PRE Django 1.7
Django lets you pass a callable as the default, and it will invoke it each time, just as you want:
from datetime import datetime, timedelta
class MyModel(models.Model):
# default to 1 day from now
my_date = models.DateTimeField(default=lambda: ...
How do Python functions handle the types of the parameters that you pass in?
...object has a type, every object knows its type, it's impossible to accidentally or deliberately use an object of a type "as if" it was an object of a different type, and all elementary operations on the object are delegated to its type.
This has nothing to do with names. A name in Python doesn't "...
Compiling with cython and mingw produces gcc: error: unrecognized command line option '-mno-cygwin'
...
It sounds like GCC 4.7.0 has finally removed the deprecated -mno-cygwin option, but distutils has not yet caught up with it. Either install a slightly older version of MinGW, or edit distutils\cygwinccompiler.py in your Python directory to remove all instan...
Override setter with arc
...piles down to (ARMv7):
.align 2
.code 16
.thumb_func "-[Article setImageURLString:]"
"-[Article setImageURLString:]":
push {r7, lr}
movw r1, :lower16:(_OBJC_IVAR_$_Article._imageURLString-(LPC7_0+4))
mov r7, sp
movt r1, :up...
bpftrace教程【官方】 - 操作系统(内核) - 清泛网 - 专注C/C++及内核技术
bpftrace教程【官方】bpftrace_tutorial该教程通过12个简单小节帮助你了解bpftrace的使用。每一小节都是一行的命令，你可以立马运行并看到运行效果。该教程系列用来介绍bpftrace的概念。关于bpftrace的完整参考，见bpftr 该教程通过12...