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LINQ Aggregate algorithm explained
This might sound lame, but I have not been able to find a really good explanation of Aggregate .
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Why do I need 'b' to encode a string with Base64?
Following this python example , I encode a string as Base64 with:
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Convert columns to string in Pandas
... your keys to strings):
In [11]: df = pd.DataFrame([['A', 2], ['A', 4], ['B', 6]])
In [12]: df.to_json()
Out[12]: '{"0":{"0":"A","1":"A","2":"B"},"1":{"0":2,"1":4,"2":6}}'
In [13]: df[0].to_json()
Out[13]: '{"0":"A","1":"A","2":"B"}'
Note: you can pass in a buffer/file to save this to, along wi...
Many-to-many relationship with the same model in rails?
...itional information with the association? (Additional fields in the join table.)
Do the associations need to be implicitly bi-directional?
(If post A is connected to post B, then post B is also connected to post A.)
That leaves four different possibilities. I'll walk over these below.
For referen...
Apply multiple functions to multiple groupby columns
The docs show how to apply multiple functions on a groupby object at a time using a dict with the output column names as the keys:
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How to get the first non-null value in Java?
...at is, is there any way to return the first non-null value of several variables?
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CSS '>' selector; what is it? [duplicate]
I've seen the "greater than" ( > ) used in CSS code a few times, but I can't work out what it does. What does it do?
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lenses, fclabels, data-accessor - which library for structure access and mutation is better
There are at least three popular libraries for accessing and manipulating fields of records. The ones I know of are: data-accessor, fclabels and lenses.
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How to iterate through two lists in parallel?
I have two iterables in Python, and I want to go over them in pairs:
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Lua简明教程 - 脚本技术 - 清泛IT论坛，有思想、有深度
...后，你会发现解释器居然不到200k，这是多么地变态啊（/bin/sh都要1M，MacOS平台），而且能和C语言非常好的互动。我很好奇得浏览了一下Lua解释器的源码，这可能是我看过最干净的C的源码了。我不想写一篇大而全的语言手册，一...