pyx/graph/axis/rater.py

   1 # -*- coding: ISO-8859-1 -*-
   2 #
   3 #
   4 # Copyright (C) 2002-2004 Jörg Lehmann <joergl@users.sourceforge.net>
   5 # Copyright (C) 2003-2004 Michael Schindler <m-schindler@users.sourceforge.net>
   6 # Copyright (C) 2002-2005 André Wobst <wobsta@users.sourceforge.net>
   7 #
   8 # This file is part of PyX (http://pyx.sourceforge.net/).
   9 #
  10 # PyX is free software; you can redistribute it and/or modify
  11 # it under the terms of the GNU General Public License as published by
  12 # the Free Software Foundation; either version 2 of the License, or
  13 # (at your option) any later version.
  14 #
  15 # PyX is distributed in the hope that it will be useful,
  16 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 # GNU General Public License for more details.
  19 #
  20 # You should have received a copy of the GNU General Public License
  21 # along with PyX; if not, write to the Free Software
  22 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  23
  24
  25 from pyx import unit, box
  26 from pyx.graph.axis import tick
  27
  28
  29 # rater
  30 # conseptional remarks:
  31 # - raters are used to calculate a rating for a realization of something
  32 # - a rating means a positive floating point value
  33 # - ratings are used to order those realizations by their suitability
  34 #   (small ratings are better)
  35 # - a rating of None means not suitable at all (those realizations should be
  36 #   thrown out)
  37
  38
  39 class cube:
  40     """a value rater
  41     - a cube rater has an optimal value, where the rate becomes zero
  42     - for a left (below the optimum) and a right value (above the optimum),
  43       the rating is value is set to 1 (modified by an overall weight factor
  44       for the rating)
  45     - the analytic form of the rating is cubic for both, the left and
  46       the right side of the rater, independently"""
  47
  48     def __init__(self, opt, left=None, right=None, weight=1):
  49         """initializes the rater
  50         - by default, left is set to zero, right is set to 3*opt
  51         - left should be smaller than opt, right should be bigger than opt
  52         - weight should be positive and is a factor multiplicated to the rates"""
  53         if left is None:
  54             left = 0
  55         if right is None:
  56             right = 3*opt
  57         self.opt = opt
  58         self.left = left
  59         self.right = right
  60         self.weight = weight
  61
  62     def rate(self, value, density):
  63         """returns a rating for a value
  64         - the density lineary rescales the rater (the optimum etc.),
  65           e.g. a value bigger than one increases the optimum (when it is
  66           positive) and a value lower than one decreases the optimum (when
  67           it is positive); the density itself should be positive"""
  68         opt = self.opt * density
  69         if value < opt:
  70             other = self.left * density
  71         elif value > opt:
  72             other = self.right * density
  73         else:
  74             return 0
  75         factor = (value - opt) / float(other - opt)
  76         return self.weight * (factor ** 3)
  77
  78
  79 class distance:
  80     # TODO: update docstring
  81     """a distance rater (rates a list of distances)
  82     - the distance rater rates a list of distances by rating each independently
  83       and returning the average rate
  84     - there is an optimal value, where the rate becomes zero
  85     - the analytic form is linary for values above the optimal value
  86       (twice the optimal value has the rating one, three times the optimal
  87       value has the rating two, etc.)
  88     - the analytic form is reciprocal subtracting one for values below the
  89       optimal value (halve the optimal value has the rating one, one third of
  90       the optimal value has the rating two, etc.)"""
  91
  92     def __init__(self, opt, weight=0.1):
  93         """inititializes the rater
  94         - opt is the optimal length (a visual PyX length)
  95         - weight should be positive and is a factor multiplicated to the rates"""
  96         self.opt = opt
  97         self.weight = weight
  98
  99     def rate(self, distances, density):
 100         """rate distances
 101         - the distances are a list of positive floats in PostScript points
 102         - the density lineary rescales the rater (the optimum etc.),
 103           e.g. a value bigger than one increases the optimum (when it is
 104           positive) and a value lower than one decreases the optimum (when
 105           it is positive); the density itself should be positive"""
 106         if len(distances):
 107             opt = unit.topt(self.opt) / density
 108             rate = 0
 109             for distance in distances:
 110                 if distance < opt:
 111                     rate += self.weight * (opt / distance - 1)
 112                 else:
 113                     rate += self.weight * (distance / opt - 1)
 114             return rate / float(len(distances))
 115
 116
 117 class rater:
 118     """a rater for ticks
 119     - the rating of axes is splited into two separate parts:
 120       - rating of the ticks in terms of the number of ticks, subticks,
 121         labels, etc.
 122       - rating of the label distances
 123     - in the end, a rate for ticks is the sum of these rates
 124     - it is useful to first just rate the number of ticks etc.
 125       and selecting those partitions, where this fits well -> as soon
 126       as an complete rate (the sum of both parts from the list above)
 127       of a first ticks is below a rate of just the number of ticks,
 128       subticks labels etc. of other ticks, those other ticks will never
 129       be better than the first one -> we gain speed by minimizing the
 130       number of ticks, where label distances have to be taken into account)
 131     - both parts of the rating are shifted into instances of raters
 132       defined above --- right now, there is not yet a strict interface
 133       for this delegation (should be done as soon as it is needed)"""
 134
 135     def __init__(self, ticks, labels, range, distance):
 136         """initializes the axis rater
 137         - ticks and labels are lists of instances of a value rater
 138         - the first entry in ticks rate the number of ticks, the
 139           second the number of subticks, etc.; when there are no
 140           ticks of a level or there is not rater for a level, the
 141           level is just ignored
 142         - labels is analogous, but for labels
 143         - within the rating, all ticks with a higher level are
 144           considered as ticks for a given level
 145         - range is a value rater instance, which rates the covering
 146           of an axis range by the ticks (as a relative value of the
 147           tick range vs. the axis range), ticks might cover less or
 148           more than the axis range (for the standard automatic axis
 149           partition schemes an extention of the axis range is normal
 150           and should get some penalty)
 151         - distance is an distance rater instance"""
 152         self.ticks = ticks
 153         self.labels = labels
 154         self.range = range
 155         self.distance = distance
 156
 157     def rateticks(self, axis, ticks, density):
 158         """rates ticks by the number of ticks, subticks, labels etc.
 159         - takes into account the number of ticks, subticks, labels
 160           etc. and the coverage of the axis range by the ticks
 161         - when there are no ticks of a level or there was not rater
 162           given in the constructor for a level, the level is just
 163           ignored
 164         - the method returns the sum of the rating results divided
 165           by the sum of the weights of the raters
 166         - within the rating, all ticks with a higher level are
 167           considered as ticks for a given level"""
 168         maxticklevel, maxlabellevel = tick.maxlevels(ticks)
 169         numticks = [0]*maxticklevel
 170         numlabels = [0]*maxlabellevel
 171         for t in ticks:
 172             if t.ticklevel is not None:
 173                 for level in range(t.ticklevel, maxticklevel):
 174                     numticks[level] += 1
 175             if t.labellevel is not None:
 176                 for level in range(t.labellevel, maxlabellevel):
 177                     numlabels[level] += 1
 178         rate = 0
 179         weight = 0
 180         for numtick, rater in zip(numticks, self.ticks):
 181             rate += rater.rate(numtick, density)
 182             weight += rater.weight
 183         for numlabel, rater in zip(numlabels, self.labels):
 184             rate += rater.rate(numlabel, density)
 185             weight += rater.weight
 186         return rate/weight
 187
 188     def raterange(self, tickrange, datarange):
 189         """rate the range covered by the ticks compared to the range
 190         of the data
 191         - tickrange and datarange are the ranges covered by the ticks
 192           and the data in graph coordinates
 193         - usually, the datarange is 1 (ticks are calculated for a
 194           given datarange)
 195         - the ticks might cover less or more than the data range (for
 196           the standard automatic axis partition schemes an extention
 197           of the axis range is normal and should get some penalty)"""
 198         return self.range.rate(tickrange, datarange)
 199
 200     def ratelayout(self, axiscanvas, density):
 201         """rate distances of the labels in an axis canvas
 202         - the distances should be collected as box distances of
 203           subsequent labels
 204         - the axiscanvas provides a labels attribute for easy
 205           access to the labels whose distances have to be taken
 206           into account
 207         - the density is used within the distancerate instance"""
 208         if axiscanvas.labels is None: # to disable any layout rating
 209             return 0
 210         if len(axiscanvas.labels) > 1:
 211             try:
 212                 distances = [axiscanvas.labels[i].boxdistance_pt(axiscanvas.labels[i+1])
 213                              for i in range(len(axiscanvas.labels) - 1)]
 214             except box.BoxCrossError:
 215                 return None
 216             return self.distance.rate(distances, density)
 217         else:
 218             return None
 219
 220
 221 class linear(rater):
 222     """a rater with predefined constructor arguments suitable for a linear axis"""
 223
 224     def __init__(self, ticks=[cube(4), cube(10, weight=0.5)],
 225                        labels=[cube(4)],
 226                        range=cube(1, weight=2),
 227                        distance=distance(1*unit.v_cm)):
 228         rater.__init__(self, ticks, labels, range, distance)
 229
 230 lin = linear
 231
 232
 233 class logarithmic(rater):
 234     """a rater with predefined constructor arguments suitable for a logarithmic axis"""
 235
 236     def __init__(self, ticks=[cube(5, right=20), cube(20, right=100, weight=0.5)],
 237                        labels=[cube(5, right=20), cube(5, right=20, weight=0.5)],
 238                        range=cube(1, weight=2),
 239                        distance=distance(1*unit.v_cm)):
 240         rater.__init__(self, ticks, labels, range, distance)
 241
 242 log = logarithmic