4.13.1 Top new questions this week

4.13.1.1 Faster derangements?

http://mathematica.stackexchange.com/questions/140794/faster-derangements

 
I wonder what is the fastest method to generate derangements? 
 
Both the Combinatorica function and Martin Ender's answer to Permutations of lists of fixed even numbers are based on filtering the  ...
 

- asked by Mr.Wizard (22 votes), answered by jkuczm (21 votes)

4.13.1.2 Why Except is so slow as compared to equivalent RegularExpression?

http://mathematica.stackexchange.com/questions/140752/why-except-is-so-slow-as-compared-to-equivalent-regularexpression

 
When comparing performance of the solutions suggested for this question I discovered that StringExpression involving Except is two orders of magnitude slower for large strings as compared to  ...
 

- asked by Alexey Popkov (18 votes), answered by Alexey Popkov (20 votes)

4.13.1.3 FrameTicks setting for "tick marks on all sides, but labels only on right and top"

http://mathematica.stackexchange.com/questions/140966/frameticks-setting-for-tick-marks-on-all-sides-but-labels-only-on-right-and-to

 
Short version: Is there a value for the FrameTicks option that retains the default tick marks on all sides, and puts tick labels only on the right and top sides? 
 
 
 
I can imagine all manner of  ...
 

- asked by kjo (15 votes), answered by Mr.Wizard (7 votes)

4.13.1.4 Quickly importing several thousands of jpg files?

http://mathematica.stackexchange.com/questions/140974/quickly-importing-several-thousands-of-jpg-files

 
I have several thousands of small .jpg files (30kb each) which I need to import into Mathematica. (I plan to use ImageDistance to investigate their differences.) I tried several ways to import these  ...
 

- asked by Kagaratsch (14 votes), answered by Szabolcs (13 votes)

4.13.1.5 Select seems unusually slow

http://mathematica.stackexchange.com/questions/140861/select-seems-unusually-slow

 
I haven't been doing nearly as much Mathematica as I really should for the past few months, and in order to get my head back in the game I've been using it to run roughshod over easy Project Euler  ...
 

- asked by Pillsy (13 votes), answered by Bob Hanlon (10 votes)

4.13.1.6 Permutations of nested parentheses (Dyck words)

http://mathematica.stackexchange.com/questions/141127/permutations-of-nested-parentheses-dyck-words

 
How would I construct a function that outputs Dyck Words? 
 
e.g. - there are 14 words in $\mathcal{D}_{8}$: 
 
`[[[[]]]], [[[][]]], [[[]][]], [[][[]]], [[[]]][], [[][][]], [][[[]]], 
[[][]][], [[]][[]],  ...
 

- asked by martin (11 votes), answered by Mr.Wizard (13 votes)

4.13.1.7 Bug: Library functions from older versions of Mathematica may crash in Mathematica 11.1 and conversely

http://mathematica.stackexchange.com/questions/140758/bug-library-functions-from-older-versions-of-mathematica-may-crash-in-mathemati

 
The following is a confirmed bug [CASE:3846875] that turned up in the prerelease 11.1.0 and is not solved in the official release. 
 
This is a small example. Execute the following commands in  ...
 

- asked by Fred Simons 11votes