unclear behavior in case of unsorted coordinates

similar (tested and flexible) functionality is available in numpy/scipy

processing/post/addDerivative.py

@@ -1,74 +0,0 @@
-#!/usr/bin/env python3
-
-import os
-import sys
-from io import StringIO
-from optparse import OptionParser
-
-import numpy as np
-
-import damask
-
-
-scriptName = os.path.splitext(os.path.basename(__file__))[0]
-scriptID   = ' '.join([scriptName,damask.version])
-
-def derivative(coordinates,what):
-
-  result = np.empty_like(what)
-
-  # use differentiation by interpolation
-  # as described in http://www2.math.umd.edu/~dlevy/classes/amsc466/lecture-notes/differentiation-chap.pdf
-
-  result[1:-1,:] = + what[1:-1,:] * (2.*coordinates[1:-1]-coordinates[:-2]-coordinates[2:]) / \
-                     ((coordinates[1:-1]-coordinates[:-2])*(coordinates[1:-1]-coordinates[2:])) \
-                   + what[2:,:] * (coordinates[1:-1]-coordinates[:-2]) / \
-                     ((coordinates[2:]-coordinates[1:-1])*(coordinates[2:]-coordinates[:-2])) \
-                   + what[:-2,:] * (coordinates[1:-1]-coordinates[2:]) / \
-                     ((coordinates[:-2]-coordinates[1:-1])*(coordinates[:-2]-coordinates[2:])) \
-
-  result[0,:]    = (what[0,:] - what[1,:]) / \
-                   (coordinates[0] - coordinates[1])
-  result[-1,:]   = (what[-1,:] - what[-2,:]) / \
-                   (coordinates[-1] - coordinates[-2])
-
-  return result
-
-
-# --------------------------------------------------------------------
-#                                MAIN
-# --------------------------------------------------------------------
-
-parser = OptionParser(option_class=damask.extendableOption, usage='%prog options [ASCIItable(s)]', description = """
-Add column(s) containing numerical derivative of requested column(s) with respect to given coordinates.
-
-""", version = scriptID)
-
-parser.add_option('-c','--coordinates',
-                  dest = 'coordinates',
-                  type = 'string', metavar='string',
-                  help = 'heading of coordinate column')
-parser.add_option('-l','--label',
-                  dest = 'labels',
-                  action = 'extend', metavar = '<string LIST>',
-                  help = 'heading of column(s) to differentiate')
-
-
-(options,filenames) = parser.parse_args()
-if filenames == []: filenames = [None]
-
-if options.coordinates is None:
-    parser.error('no coordinate column specified.')
-if options.labels is None:
-    parser.error('no data column specified.')
-
-for name in filenames:
-    damask.util.report(scriptName,name)
-
-    table = damask.Table.load(StringIO(''.join(sys.stdin.read())) if name is None else name)
-    for label in options.labels:
-        table = table.add('d({})/d({})'.format(label,options.coordinates),
-                          derivative(table.get(options.coordinates),table.get(label)),
-                          scriptID+' '+' '.join(sys.argv[1:]))
-
-    table.save((sys.stdout if name is None else name), legacy=True)