TL: generic FieldsIO class for n-dimensional rectilinear grids + VTK support (#533)

* TL: simplified fieldsIO to two generic classes (Scalar + Rectilinear)

* TL: trying something

* TL: restriction to python 3.11

* TL: another try

* TL: I'm dumb

* TL: yet another try ...

* TL: added vtk support for 3D VTR files

* TL: avoided clashing name, gitignore update

* TL: you gotta be kiding me ...

* TL: VTK output support for Rectilinear FieldsIO

* TL: added documentation

* TL: polished documentation

* TL: minor typo

* TL: refactoring following thomas's suggestions

* TL: minor typo

* TL: corrected Rectilinear.toVTR for paraview groups

Author: tlunet

.gitignore

@@ -11,6 +11,7 @@ step_*.png
 *_data.json
 !_dataRef.json
 *.pysdc
+*.vtr
 
 # Created by https://www.gitignore.io
 

etc/environment-base.yml

@@ -10,6 +10,7 @@ dependencies:
   - sympy>=1.0
   - numba>=0.35
   - dill>=0.2.6
+  - vtk
   - pip
   - pip:
     - qmat>=0.1.8

pySDC/helpers/blocks.py

@@ -1,3 +1,6 @@
+import numpy as np
+
+
 class BlockDecomposition(object):
     """
     Class decomposing a cartesian space domain (1D to 3D) into a given number of processors.
@@ -92,16 +95,9 @@ def __init__(self, nProcs, gridSizes, algo="Hybrid", gRank=None, order="C"):
 
     @property
     def ranks(self):
-        gRank, order = self.gRank, self.order
-        assert gRank is not None, "gRank attribute need to be set"
-        dim, nBlocks = self.dim, self.nBlocks
-        if dim == 1:
-            return (gRank,)
-        elif dim == 2:
-            div = nBlocks[-1] if order == "C" else nBlocks[0]
-            return (gRank // div, gRank % div)
-        else:
-            raise NotImplementedError(f"dim={dim}")
+        assert self.gRank is not None, "gRank attribute needs to be set"
+        cart = np.arange(np.prod(self.nBlocks)).reshape(self.nBlocks, order=self.order)
+        return list(np.argwhere(cart == self.gRank)[0])
 
     @property
     def localBounds(self):