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Algorithm to get the excel-like column name of a number
I'm working on a script that generate some Excel documents and I need to convert a number into its column name equivalent. For example:
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How to add an extra column to a NumPy array
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I think a more straightforward solution and faster to boot is to do the following:
import numpy as np
N = 10
a = np.random.rand(N,N)
b = np.zeros((N,N+1))
b[:,:-1] = a
And timings:
In [23]: N = 10
In [24]: a = np.random.rand(N,N)
In [25]: %timeit b = np.hstac...
Color text in terminal applications in UNIX [duplicate]
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printf(KMAG "magenta\n"); is much cleaner and faster than using %s.
– user142019
Feb 26 '11 at 12:43
13
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How to insert a newline in front of a pattern?
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This works in bash and zsh, tested on Linux and OS X:
sed 's/regexp/\'$'\n/g'
In general, for $ followed by a string literal in single quotes bash performs C-style backslash substitution, e.g. $'\t' is translated to a literal tab. Plus, sed ...
Get first n characters of a string
...hat's the fastest way to trim a string to a specific number of characters, and append '...' if needed?
19 Answers
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Randomize a List
What is the best way to randomize the order of a generic list in C#? I've got a finite set of 75 numbers in a list I would like to assign a random order to, in order to draw them for a lottery type application.
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Why is pow(a, d, n) so much faster than a**d % n?
I was trying to implement a Miller-Rabin primality test , and was puzzled why it was taking so long (> 20 seconds) for midsize numbers (~7 digits). I eventually found the following line of code to be the source of the problem:
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Converting newline formatting from Mac to Windows
...In conclusion, simply replace every occurence of \n by \r\n.
Both unix2dos and dos2unix are not by default available on Mac OSX.
Fortunately, you can simply use Perl or sed to do the job:
sed -e 's/$/\r/' inputfile > outputfile # UNIX to DOS (adding CRs)
sed -e 's/\r$//' inputfil...
Change values while iterating
... prints you completely different memory locations for the value from range and the actual
value in the slice:
0xf84000f010 vs. 0x7f095ed0bf68
0xf84000f014 vs. 0x7f095ed0bf68
0xf84000f018 vs. 0x7f095ed0bf68
So the only thing you can do is to either use pointers or the index, as already proposed ...
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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