4.18.1 Top new questions this week

4.18.1.1 Count works differently depending on how an association was created

https://mathematica.stackexchange.com/questions/144813/count-works-differently-depending-on-how-an-association-was-created

 
Bug introduced in 10.4 and persisting through 11.1.1 
 
 
 
I create two associations, that are supposed to be exactly the same. And then I want to count the elements at the second level. And I get  ...
 

- asked by Stitch (19 votes), answered by WReach (12 votes)

4.18.1.2 Why is Plus so much slower than Total?

https://mathematica.stackexchange.com/questions/145019/why-is-plus-so-much-slower-than-total

 
Why is Plus so much slower than total for summing lists? 
 
list = RandomReal[1, 10000000]; 
AbsoluteTiming[Plus @@ list] 
AbsoluteTiming[Total[list]] 
 
 
Output: 
 
{1.67408, 5.00073*10^6} 
{0.00570379,  ...
 

- asked by Jorge Perez (14 votes), answered by Shadowray (17 votes)

4.18.1.3 Delete duplicates from list of lists as if on a necklace

https://mathematica.stackexchange.com/questions/144696/delete-duplicates-from-list-of-lists-as-if-on-a-necklace

 
Given a list of lists of integers, all of the same length, I want to regard two elements as equivalent if one is the rotated and/or reflected version of another (that is, if the two lists are the same  ...
 

- asked by rogerl (13 votes), answered by Shadowray (13 votes)

4.18.1.4 Exchanging numpy arrays between Python and Mathematica?

https://mathematica.stackexchange.com/questions/144770/exchanging-numpy-arrays-between-python-and-mathematica

 
I've been using np.savetxt(location, result, delimiter=',') in Python followed by Import[location,"CSV"] in Mathematica. Some of my files are around 1GB, opening seems a bit slow, what else do people  ...
 

- asked by Yaroslav Bulatov (12 votes), answered by xslittlegrass (16 votes)

4.18.1.5 How to plot planar graphs in a visually pleasing way?

https://mathematica.stackexchange.com/questions/144594/how-to-plot-planar-graphs-in-a-visually-pleasing-way

 
Cross posted to Wolfram Community 
 
 
 
Mathematica has a layout algorithm to plot planar graphs without edge crossings.  This typically produces an ugly triangular layout where some vertices and edges  ...
 

- asked by Szabolcs (11 votes), answered by Szabolcs (6 votes)

4.18.1.6 Where are my Cloud Credits going?

https://mathematica.stackexchange.com/questions/144859/where-are-my-cloud-credits-going

 
In less than a month I've used 5k cloud credits (half of my quota) and all I did was deploying a bunch of static notebooks with CloudDeploy[CurrentNotebook[],permissions->Public] (more  ...
 

- asked by Yaroslav Bulatov 10votes

4.18.1.7 Mathematica erroneously says this integral does not converge

https://mathematica.stackexchange.com/questions/144965/mathematica-erroneously-says-this-integral-does-not-converge

 
Mathematica (as of v. 11.1.0) does not recognize that this special case of Frullani's integral converges: 
 
Integrate[(ArcTan[a*x] - ArcTan[b*x])/x, {x, 0, Infinity}] 
(* Integrate::idiv: Integral of  ...
 

- asked by Pillsy (10 votes), answered by Michael E2 (16 votes)