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What does the “yield” keyword do?

...ou create the method of the node object that will return the generator def _get_child_candidates(self, distance, min_dist, max_dist): # Here is the code that will be called each time you use the generator object: # If there is still a child of the node object on its left # AND if the d...
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How to import the class within the same directory or sub directory?

... Python 2 Make an empty file called __init__.py in the same directory as the files. That will signify to Python that it's "ok to import from this directory". Then just do... from user import User from dir import Dir The same holds true if the files are in a...
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Count number of records returned by group by

...rGroup, COUNT(*) OVER () AS TotalRecords from temptable group by column_1, column_2, column_3, column_4 share | improve this answer | follow | ...
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How do I filter query objects by date range in Django?

... Use Sample.objects.filter(date__range=["2011-01-01", "2011-01-31"]) Or if you are just trying to filter month wise: Sample.objects.filter(date__year='2011', date__month='01') Edit As Bernhard Vallant said, if you want a query...
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How do you calculate the average of a set of circular data? [closed]

...e, A, from a set of angle measurements a[i] 0<=i sum_i_from_1_to_N sin(a[i]) a = arctangent --------------------------- sum_i_from_1_to_N cos(a[i]) The method given by starblue is computationally equivalent, but his reasons are clearer and probably program...
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Why prefer two's complement over sign-and-magnitude for signed numbers?

...icle on two's complement for the full answer: en.wikipedia.org/wiki/Two%27s_complement. The short answer is the MSB 1 indicates -8, and the remaining three 1s indicate 4, 2, and 1, respectively, so -8+4+2+1 = -1. – Welbog Aug 23 '16 at 13:33 ...
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List all indexes on ElasticSearch server?

...ise list of all indices in your cluster, call curl http://localhost:9200/_aliases this will give you a list of indices and their aliases. If you want it pretty-printed, add pretty=true: curl http://localhost:9200/_aliases?pretty=true The result will look something like this, if your indices ...
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How does deriving work in Haskell?

... Haskell Wiki: In this example we use the following Haskell code $(gen_render ''Body) to produce the following instance: instance TH_Render Body where render (NormalB exp) = build 'normalB exp render (GuardedB guards) = build 'guardedB guards The function gen_render above is d...
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Instance attribute attribute_name defined outside __init__

.... We expect to find all the attributes an instance may have by reading its __init__ method. You may still want to split initialization into other methods though. In such case, you can simply assign attributes to None (with a bit of documentation) in the __init__ then call the sub-initialization met...
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What does $_ mean in PowerShell?

...ich is called $PSItem in Powershell 3 and newer. 1,2,3 | %{ write-host $_ } or 1,2,3 | %{ write-host $PSItem } For example in the above code the %{} block is called for every value in the array. The $_ or $PSItem variable will contain the current value. ...