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The “backspace” escape character '\b': unexpected behavior?
...mp;R , and I learned something within the first few pages, that there is a backspace escape character, \b .
5 Answers
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Circle line-segment collision detection algorithm?
I have a line from A to B and a circle positioned at C with the radius R.
27 Answers
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Do I need to explicitly call the base virtual destructor?
...I am implementing the destructor again as virtual on the inheriting class, but do I need to call the base destructor?
7 Ans...
From ND to 1D arrays
...(for an 1D iterator):
In [12]: a = np.array([[1,2,3], [4,5,6]])
In [13]: b = a.ravel()
In [14]: b
Out[14]: array([1, 2, 3, 4, 5, 6])
Note that ravel() returns a view of a when possible. So modifying b also modifies a. ravel() returns a view when the 1D elements are contiguous in memory, but wou...
Scala type programming resources
...stion , Scala's type system is Turing complete . What resources are available that enable a newcomer to take advantage of the power of type-level programming?
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Pairwise crossproduct in Python [duplicate]
How can I get the list of cross product pairs from a list of arbitrarily long lists in Python?
3 Answers
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Conditionally Remove Dataframe Rows with R [duplicate]
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Logic index:
d<-d[!(d$A=="B" & d$E==0),]
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SQL中使用update inner join和delete inner join；Oracle delete join替代...
...来做更新和删除操作非常有用.
例子：
Sql代码
update tb_User
set pass='' --此处pass前不要加 tb_User 别名usr
from tb_User usr
inner join tb_Address addr on usr.nAddressFK = addr.nAddressID
where usr.id=123
update的格式是
update t1 set t1.name=’Liu&r...
Pandas DataFrame Groupby two columns and get counts
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Followed by @Andy's answer, you can do following to solve your second question:
In [56]: df.groupby(['col5','col2']).size().reset_index().groupby('col2')[[0]].max()
Out[56]:
0
col2
A 3
B 2
C 1
D 3
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What are all the common undefined behaviours that a C++ programmer should know about? [closed]
What are all the common undefined behaviours that a C++ programmer should know about?
11 Answers
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