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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...
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...
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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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 get the first non-null value in Java?
...at is, is there any way to return the first non-null value of several variables?
12 Answers
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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?
7 A...
How to iterate through two lists in parallel?
I have two iterables in Python, and I want to go over them in pairs:
8 Answers
8
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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...
What is an undefined reference/unresolved external symbol error and how do I fix it?
What are undefined reference/unresolved external symbol errors? What are common causes and how to fix/prevent them?
34 Answ...
pandas: How do I split text in a column into multiple rows?
...file and the next to last column has a string of text that I want to split by a specific delimiter. I was wondering if there is a simple way to do this using pandas or python?
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