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Mapping two integers to one, in a unique and deterministic way
Imagine two positive integers A and B. I want to combine these two into a single integer C.
18 Answers
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How to group dataframe rows into list in pandas groupby?
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You can do this using groupby to group on the column of interest and then apply list to every group:
In [1]: df = pd.DataFrame( {'a':['A','A','B','B','B','C'], 'b':[1,2,5,5,4,6]})
df
Out[1]:
a b
0 A 1
1 A 2
2 B 5
3 B 5
4 B 4
5 ...
Good MapReduce examples [closed]
...o count words in a long text with MapReduce" task. I found this wasn't the best example to give others an impression of how powerful this tool can be.
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What is the difference between “INNER JOIN” and “OUTER JOIN”?
... with no duplicates, which is a very common case:
An inner join of A and B gives the result of A intersect B, i.e. the inner part of a Venn diagram intersection.
An outer join of A and B gives the results of A union B, i.e. the outer parts of a Venn diagram union.
Examples
Suppose you have two ...
Circular dependency in Spring
How does Spring resolve this: bean A is dependent on bean B, and bean B on bean A.
12 Answers
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is vs typeof
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This should answer that question, and then some.
The second line, if (obj.GetType() == typeof(ClassA)) {}, is faster, for those that don't want to read the article.
(Be aware that they don't do the same thing)
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How does `is_base_of` work?
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If they are related
Let's for a moment assume that B is actually a base of D. Then for the call to check, both versions are viable because Host can be converted to D* and B*. It's a user defined conversion sequence as described by 13.3.3.1.2 from Host<B, D> to D* and B*...
How can we match a^n b^n with Java regex?
... to say, YES! You can most certainly write a Java regex pattern to match anbn. It uses a positive lookahead for assertion, and one nested reference for "counting".
Rather than immediately giving out the pattern, this answer will guide readers through the process of deriving it. Various hints are giv...
What is the difference between instanceof and Class.isAssignableFrom(…)?
Which of the following is better?
14 Answers
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What is object slicing?
Someone mentioned it in the IRC as the slicing problem.
18 Answers
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