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Why are elementwise additions much faster in separate loops than in a combined loop?
Suppose a1 , b1 , c1 , and d1 point to heap memory and my numerical code has the following core loop.
10 Answers
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count the frequency that a value occurs in a dataframe column
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Use groupby and count:
In [37]:
df = pd.DataFrame({'a':list('abssbab')})
df.groupby('a').count()
Out[37]:
a
a
a 2
b 3
s 2
[3 rows x 1 columns]
See the online docs: http://pandas.pydata.org/pandas-docs/stable/groupby.htm...
Return anonymous type results?
Using the simple example below, what is the best way to return results from multiple tables using Linq to SQL?
16 Answers
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Listing all permutations of a string/integer
...f interviews though) is to take a string or an integer and list every possible permutation.
28 Answers
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SQL JOIN vs IN performance?
...g a JOIN or an IN will give me the correct results... Which typically has better performance and why? How much does it depend on what database server you are running? (FYI I am using MSSQL)
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Math - mapping numbers
How do I map numbers, linearly, between a and b to go between c and d.
9 Answers
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Fast way of counting non-zero bits in positive integer
I need a fast way to count the number of bits in an integer in python.
My current solution is
9 Answers
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Simultaneously merge multiple data.frames in a list
...o merge. The issue here is that each data.frame differs in terms of the number of rows and columns, but they all share the key variables (which I've called "var1" and "var2" in the code below). If the data.frames were identical in terms of columns, I could merely rbind , for which plyr's rbind...
How are the points in CSS specificity calculated
Researching specificity I stumbled upon this blog - http://www.htmldog.com/guides/cssadvanced/specificity/
7 Answers
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Where does 'Hello world' come from?
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Brian Kernighan actually wrote the first "hello, world" program as part of the documentation for the BCPL programming language developed by Martin Richards. BCPL was used while C was being developed at Bell Labs a few years b...