7.20.1 Top new questions this week

7.20.1.1 How to make Mathematica read in CSV as fast as Python's Pandas

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=249369

I have many big CSV files for processing in Mathematica. 
And each time loading them into Mathematica takes a long time. 
Meanwhile, it takes much less time using Pandas under Python. 
For example, ... 
[import] [python] [csv-format]
 

asked by sunt05 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=260 17 votes

answered by George Varnavides https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=41179 9 votes

7.20.1.2 How to construct a tree from a preorder traversal

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=249256

The list 
 t1 = {1, 2, 3, 3, 4, 4, 3, 3, 4, 3, 3, 2, 3, 4, 2, 3, 2}; 
 
might be derived from a pre-order traversal of 
... 
[list-manipulation] [trees]
 

asked by High Performance Mark https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=519 8 votes

answered by Michael E2 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4999 13 votes

7.20.1.3 TimeSeriesShift seems broken -- is there a stable workaround?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=249275

Issue 1: Certain dates shift into the same date, leading to duplicated keys, rendering the time series unusable: 
... 
[functions] [bugs]
 

asked by secr https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=80404 7 votes

answered by Gosia https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5372 0 votes

7.20.1.4 Unable to solve nonlinear PDE with NDSolve

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=249356

Lately, I've been trying to solve the following PDE: 
\begin{equation} -v_0 |\nabla F| + {\bf f}\cdot \nabla F +D\nabla^2F = -1 
\end{equation} 
inside a 2D region between two disks both centered in the ... 
[differential-equations] [finite-element-method] [boundary-conditions]
 

asked by lorenzop https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=74662 5 votes

answered by user21 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=18437 6 votes

7.20.1.5 Sort list by a condition on parameters

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=249332

Consider the following list 
 list={{{0,0,0},0},{{0,0,1},a},{{0,0,-1},-a},{{1,0,1},b},{{1,0,0},-b},{{1,1,1},a+b},{{1,1,1},a-b},{{-1,0,-1},{-a-b}},{{-1,0,-1},{-a+b}}}; 
 ... 
[list-manipulation]
 

asked by jarhead https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=26549 5 votes

answered by Lukas Lang https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=36508 4 votes

7.20.1.6 AceFEM: Divergence in iterative procedure (Newton-Raphson) for fine meshes

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=249175

I am trying to model a problem of a nearly incompressible $10~\rm{m} \times 2~\rm{m}$ beam with a uniformly distributed end load. The beam has a Young's modulus of $200~\rm{Pa}$ and a Poisson's ratio ... 
[differential-equations] [equation-solving] [finite-element-method] [acegen] [convergence]
 

asked by DvanHuyssteen https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=69831 5 votes

7.20.1.7 Efficient computation of Hopf index

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=249168

I am trying to check using Mathematica the following result: 
$$-\frac{1}{4\pi^2}\int_{0}^{2\pi}\int_{0}^{2\pi}\int_{0}^{2\pi} \mathbf{F}\cdot\mathbf{A}\;dk_x dk_y dk_z=1,\quad\text{where}$$ 
$$z_{\... 
[calculus-and-analysis] [functions] [numerical-integration]
 

asked by Hyeongmuk LIM https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=80354 5 votes

answered by Fidel I. Schaposnik https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=45839 4 votes