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Results tagged with performance-tuning
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user 19991
Questions on optimizing Mathematica code for higher performance. This may mean faster execution, lower memory usage or both. Not to be confused with mathematical optimization.
3
votes
FileNames becomes extremely slow when there are large number of files under a directory
Under windows system this is the way to get huge number of filenames under a directory:
filenamesFast[dir_]:=
Module[{txtname="\\temp-alldirs.txt"},
Run["dir \""<>dir<>"\" /b >\""<>dir<>txtname<>"\""] …
- 2,745
5
votes
1
answer
186
views
FileNames becomes extremely slow when there are large number of files under a directory
I have a directory on my portable hard drive, with around 350000 files under it (there is no subdirectory, only files). I want to get all the file dirs so use
filedirs=FileNames["*",mydir]
However, …
- 2,745
20
votes
1
answer
782
views
The efficiency compare between Flatten[#, 1] & and Join @@ # &
Err.. Often I met the situation to join lists at the first level and I used to just Flatten[#, 1] & @ them. However, I found (when glance over the mathematica.stackexchange.com) someone else prefers J …
- 2,745
12
votes
2
answers
311
views
why MeanFilter is nearly 100 times slower than MovingAverage for 1D array?
I used to average over my data with MeanFilter before I learn about MovingAverage and thought that these two functions are similar except that MeanFilter is more powerful for its ability to deal with …
- 2,745
3
votes
2
answers
93
views
union several arrays of same flag(date for example) efficiently
Suppose I have several arrays from data files which look like:
arrayi = {{datei1, xi11, xi21, ...}, {datei2, xi12, xi22, ...}, ..., {datein, xi1n, xi2n ,...}}
The arrayis are from different data so …
- 2,745
1
vote
1
answer
112
views
why URLFetch is slow when encapsulated by module and how to fix it [closed]
I'm using Mathematica 10.0.2 on Win7.
I'm writing some program to crawl etymology of words on http://www.etymonline.com/. Below lies the example code:
str = URLFetch[
"http://www.etymonline.com/inde …
- 2,745
1
vote
0
answers
46
views
Does NonlinearModelFit result stores FitResiduals? [closed]
I fits a long data series with a complex model by NonlinearModelFit:
fitnlm = NonlinearModelFit[...]
Then I can use fitnlm["BestFitParameters"] to get parameters, use fitnlm["Response"] to view ori …
- 2,745