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How do you query for “is not null” in Mongo?
...
This will return all documents with a key called "IMAGE URL", but they may still have a null value.
db.mycollection.find({"IMAGE URL":{$exists:true}});
This will return all documents with both a key called "IMAGE URL" and a non-null value.
d...
“Large data” work flows using pandas
... one contains different fields, or do they have some records per file with all of the fields in each file?
Do you ever select subsets of rows (records) based on criteria (e.g. select the rows with field A > 5)? and then do something, or do you just select fields A, B, C with all of the records (a...
Sass or Compass without ruby?
...uage. At this point, you can use the Sass engine in Ruby, Node.js, Python, PHP, Java, .NET and others. For more information, visit libSass. Also, your IDE might have a plugin which would support Sass, without the need of ruby by using the libSass.
The original answer below may or may not apply to y...
What is the most efficient string concatenation method in python?
... idiomatic and thus easier for other python programmers to understand.
Finally, the golden rule of optimization: don't optimize unless you know you need to, and measure rather than guessing.
You can measure different methods using the timeit module. That can tell you which is fastest, instead of r...
How to request Administrator access inside a batch file
...s method doesn't forward arguments. Do you know How that can be done? Basically what I observe is that on the first line %1 has some value and on the last line %1 is null. I need to forward the arguments.
– prongs
Jan 11 '13 at 11:54
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What's the bad magic number error?
...the pyc file or trying to run a pyc from a different version of python (usually later) than your interpreter.
If they are your pyc files, just delete them and let the interpreter re-compile the py files. On UNIX type systems, that could be something as simple as:
rm *.pyc
or:
find . -name '*.py...
How to avoid circular imports in Python? [duplicate]
....py
Types of circular import problems
Circular import dependencies typically fall into two categories depending
on what you're trying to import and where you're using it inside each
module. (And whether you're using python 2 or 3).
1. Errors importing modules with circular imports
In some cases...
How to resize superview to fit all subviews with autolayout?
...n a UITableViewCell (to determine row height for example) then you should call it against your cell contentView and grab the height.
Further considerations exist if you have one or more UILabel's in your view that are multiline. For these it is imperitive that the preferredMaxLayoutWidth propert...
Algorithm to detect corners of paper sheet in photo
...n are awesome, move to them as soon as possible. :D
Instead of removing small objects and or noise, lower the canny restraints, so it accepts more edges, and then find the largest closed contour (in OpenCV use findcontour() with some simple parameters, I think I used CV_RETR_LIST). might still stru...
What is the meaning of “__attribute__((packed, aligned(4))) ”
...gned(1))) sSampleStruct;
so the above specified gcc attribute does not allow the structure padding. so the size will be 8 bytes.
If you wish to do the same for all the structures, simply we can push the alignment value to stack using #pragma
#pragma pack(push, 1)
//Structure 1
......
//Stru...