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How to append rows to an R data frame
...sive insight than system.time:
library(microbenchmark)
microbenchmark(f1(1000), f3(1000), f4(1000), times = 5)
# Unit: milliseconds
# expr min lq median uq max neval
# f1(1000) 1024.539618 1029.693877 1045.972666 1055.25931 1112.769176 5
# f3(1000) ...
How to initialise memory with new operator in C++?
...ay of type int with the new operator, how can I initialise them all to 0 without looping through them all myself? Should I just use memset ? Is there a “C++” way to do it?
...
Set cURL to use local virtual hosts
...icitly for this: --resolve
Instead of curl -H 'Host: yada.com' http://127.0.0.1/something
use curl --resolve 'yada.com:80:127.0.0.1' http://yada.com/something
What's the difference, you ask?
Among others, this works with HTTPS. Assuming your local server has a certificate for yada.com, the firs...
Can't connect to local MySQL server through socket '/tmp/mysql.sock
...
PratyayPratyay
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float64 with pandas to_csv
...
df.to_csv('pandasfile.csv', float_format='%.3f')
or, if you don't want 0.0001 to be rounded to zero:
df.to_csv('pandasfile.csv', float_format='%g')
will give you:
Bob,0.085
Alice,0.005
in your output file.
For an explanation of %g, see Format Specification Mini-Language.
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How to specify Composer install path?
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140
It seems that you can define the vendor dir to be something else (plugins in your case):
{
...
How do I get time of a Python program's execution?
...s that your program takes at least a tenth of second to run.
Prints:
--- 0.764891862869 seconds ---
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Add unique constraint to combination of two columns
...g an exception (exceptions are expensive).
http://www.sqlperformance.com/2012/08/t-sql-queries/error-handling
http://www.mssqltips.com/sqlservertip/2632/checking-for-potential-constraint-violations-before-entering-sql-server-try-and-catch-logic/
If you want to prevent exceptions from bubbling up ...
How do you convert a byte array to a hexadecimal string, and vice versa?
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1402
Either:
public static string ByteArrayToString(byte[] ba)
{
StringBuilder hex = new StringBu...
Cluster analysis in R: determine the optimal number of clusters
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1024
If your question is how can I determine how many clusters are appropriate for a kmeans analysi...