6.23.1 Top new questions this week

6.23.1.1 What is a good way of perfoming operations on specified columns of a table with many columns

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=230854

If I have a table of data and I want to do a specific operation on say the third column, I usually do something like this: 
... 
[list-manipulation] [table] [column]
 

asked by Q.P. https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=27119 11 votes

answered by kglr https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=125 8 votes

6.23.1.2 Quickest way to test whether array is constant

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=230971

At the moment I use  Length[ DeleteDuplicates[ array ] ] == 1  to check whether an array is constant, but I'm not sure whether this is optimal. 
What would be the ... 
[performance-tuning] [array]
 

asked by Gert https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=27889 11 votes

answered by Sjoerd Smit https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=43522 9 votes

6.23.1.3 Solving a rotating combination lock puzzle

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=230749

The following puzzle appears in The House of da Vinci II and I thought it might be interesting to tackle in Mathematica: 
 
There are numbers marked on four rotating cylinders. These numbers must add up ... 
[combinatorics] [searching] [puzzle]
 

asked by flinty https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=72682 9 votes

answered by C. E. https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=731 8 votes

6.23.1.4 Shortest way to make a checkerboard pattern

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=230988

I'm looking for the shortest (in terms of characters) code snippet to make an n-square checkerboard.  Here's my first try (comes in at 72 characters): 
... 
[plotting] [graphics] [style] [pattern-filling]
 

asked by M.R. https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=403 7 votes

answered by kglr https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=125 9 votes

6.23.1.5 Smoothing the Region

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=230725

There is a 2D Pi 
 
I successed transformed it to 3D. 
... 
[regions] [mesh] [visualization] [3d-printing]
 

asked by partida https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=15961 7 votes

answered by xzczd https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1871 9 votes

6.23.1.6 How to replace only the isolated variable x

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=230717

I want to replace the variable  x  in the result, not  x  in unrelated  x[i] . 
... 
[replacement]
 

asked by A little mouse on the pampashttps://mathematica.stackexchange.com/landing/r/digest?cta=user&id=42417 7 votes

answered by kglr https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=125 11 votes

6.23.1.7 Counting Elements in Multiple Lists

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=230864

How to build a table that counts how many times each element in mainlist occurs in lst1, lst2, lst3, lst4 and which lst1, lst2, lst3, lst4 contains that element. For example, in mainlist, element ... 
[list-manipulation]
 

asked by PRG https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=42700 6 votes

answered by kglr https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=125 7 votes