pyx/graph/axis/tick.py

   1 #!/usr/bin/env python
   2 # -*- coding: ISO-8859-1 -*-
   3 #
   4 #
   5 # Copyright (C) 2002-2004 Jörg Lehmann <joergl@users.sourceforge.net>
   6 # Copyright (C) 2003-2004 Michael Schindler <m-schindler@users.sourceforge.net>
   7 # Copyright (C) 2002-2004 André Wobst <wobsta@users.sourceforge.net>
   8 #
   9 # This file is part of PyX (http://pyx.sourceforge.net/).
  10 #
  11 # PyX is free software; you can redistribute it and/or modify
  12 # it under the terms of the GNU General Public License as published by
  13 # the Free Software Foundation; either version 2 of the License, or
  14 # (at your option) any later version.
  15 #
  16 # PyX is distributed in the hope that it will be useful,
  17 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 # GNU General Public License for more details.
  20 #
  21 # You should have received a copy of the GNU General Public License
  22 # along with PyX; if not, write to the Free Software
  23 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  24
  25
  26 import sys
  27
  28 # test automatic long conversion
  29 try:
  30     sys.maxint+1
  31     autolong = 1
  32 except OverflowError:
  33     autolong = 0
  34
  35
  36 class rational:
  37     """rational class performing some basic rational arithmetics
  38     the axis partitioning uses rational arithmetics (with infinite accuracy)
  39     basically it contains self.num and self.denom"""
  40
  41     def initfromstring(self, s):
  42         "converts a string 0.123 into a rational"
  43         expparts = s.strip().replace("E", "e").split("e")
  44         if len(expparts) > 2:
  45             raise ValueError("multiple 'e' found in '%s'" % s)
  46         commaparts = expparts[0].split(".")
  47         if len(commaparts) > 2:
  48             raise ValueError("multiple '.' found in '%s'" % expparts[0])
  49         if len(commaparts) == 1:
  50             commaparts = [commaparts[0], ""]
  51         self.num = 1
  52         if autolong:
  53             self.denom = 10 ** len(commaparts[1])
  54         else:
  55             self.denom = 10L ** len(commaparts[1])
  56         neg = len(commaparts[0]) and commaparts[0][0] == "-"
  57         if neg:
  58             commaparts[0] = commaparts[0][1:]
  59         elif len(commaparts[0]) and commaparts[0][0] == "+":
  60             commaparts[0] = commaparts[0][1:]
  61         if len(commaparts[0]):
  62             if not commaparts[0].isdigit():
  63                 raise ValueError("unrecognized characters in '%s'" % s)
  64             try:
  65                 x = int(commaparts[0])
  66             except:
  67                 x = long(commaparts[0])
  68         else:
  69             x = 0
  70         if len(commaparts[1]):
  71             if not commaparts[1].isdigit():
  72                 raise ValueError("unrecognized characters in '%s'" % s)
  73             try:
  74                 y = int(commaparts[1])
  75             except:
  76                 y = long(commaparts[1])
  77         else:
  78             y = 0
  79         self.num = x*self.denom + y
  80         if neg:
  81             self.num = -self.num
  82         if len(expparts) == 2:
  83             neg = expparts[1][0] == "-"
  84             if neg:
  85                 expparts[1] = expparts[1][1:]
  86             elif expparts[1][0] == "+":
  87                 expparts[1] = expparts[1][1:]
  88             if not expparts[1].isdigit():
  89                 raise ValueError("unrecognized characters in '%s'" % s)
  90             if neg:
  91                 if autolong:
  92                     self.denom *= 10 ** int(expparts[1])
  93                 else:
  94                     self.denom *= 10L ** int(expparts[1])
  95             else:
  96                 if autolong:
  97                     self.num *= 10 ** int(expparts[1])
  98                 else:
  99                     self.num *= 10L ** int(expparts[1])
 100
 101     def initfromfloat(self, x, floatprecision):
 102         "converts a float into a rational with finite resolution"
 103         if floatprecision < 0:
 104             raise RuntimeError("float resolution must be non-negative")
 105         self.initfromstring(("%%.%ig" % floatprecision) % x)
 106
 107     def __init__(self, x, power=1, floatprecision=10):
 108         """initializes a rational
 109         - rational=(num/denom)**power
 110         - x must be one of:
 111           - a string (like "1.2", "1.2e3", "1.2/3.4", etc.)
 112           - a float (converted using floatprecision)
 113           - a sequence of two integers
 114           - a rational instance"""
 115         if power == 0:
 116             self.num = 1
 117             self.denom = 1
 118             return
 119         try:
 120             # does x behave like a number
 121             x + 0
 122         except:
 123             try:
 124                 # does x behave like a string
 125                 x + ""
 126             except:
 127                 try:
 128                     # x might be a tuple
 129                     self.num, self.denom = x
 130                 except:
 131                     # otherwise it should have a num and denom
 132                     self.num, self.denom = x.num, x.denom
 133             else:
 134                 # x is a string
 135                 fraction = x.split("/")
 136                 if len(fraction) > 2:
 137                     raise ValueError("multiple '/' found in '%s'" % x)
 138                 self.initfromstring(fraction[0])
 139                 if len(fraction) == 2:
 140                     self /= rational(fraction[1])
 141         else:
 142             # x is a number
 143             self.initfromfloat(x, floatprecision)
 144         if not self.denom: raise ZeroDivisionError("zero denominator")
 145         if power == -1:
 146             self.num, self.denom = self.denom, self.num
 147         elif power < -1:
 148             if autolong:
 149                 self.num, self.denom = self.denom ** (-power), self.num ** (-power)
 150             else:
 151                 self.num, self.denom = long(self.denom) ** (-power), long(self.num) ** (-power)
 152         elif power > 1:
 153             if autolong:
 154                 self.num = self.num ** power
 155                 self.denom = self.denom ** power
 156             else:
 157                 self.num = long(self.num) ** power
 158                 self.denom = long(self.denom) ** power
 159
 160     def __cmp__(self, other):
 161         try:
 162             return cmp(self.num * other.denom, other.num * self.denom)
 163         except:
 164             return cmp(float(self), other)
 165
 166     def __abs__(self):
 167         return rational((abs(self.num), abs(self.denom)))
 168
 169     def __mul__(self, other):
 170         return rational((self.num * other.num, self.denom * other.denom))
 171
 172     def __imul__(self, other):
 173         self.num *= other.num
 174         self.denom *= other.denom
 175         return self
 176
 177     def __div__(self, other):
 178         return rational((self.num * other.denom, self.denom * other.num))
 179
 180     def __idiv__(self, other):
 181         self.num *= other.denom
 182         self.denom *= other.num
 183         return self
 184
 185     def __float__(self):
 186         "caution: avoid final precision of floats"
 187         return float(self.num) / self.denom
 188
 189     def __str__(self):
 190         return "%i/%i" % (self.num, self.denom)
 191
 192
 193 class tick(rational):
 194     """tick class
 195     a tick is a rational enhanced by
 196     - self.ticklevel (0 = tick, 1 = subtick, etc.)
 197     - self.labellevel (0 = label, 1 = sublabel, etc.)
 198     - self.label (a string) and self.labelattrs (a list, defaults to [])
 199     When ticklevel or labellevel is None, no tick or label is present at that value.
 200     When label is None, it should be automatically created (and stored), once the
 201     an axis painter needs it. Classes, which implement _Itexter do precisely that."""
 202
 203     def __init__(self, x, ticklevel=0, labellevel=0, label=None, labelattrs=[], **kwargs):
 204         """initializes the instance
 205         - see class description for the parameter description
 206         - **kwargs are passed to the rational constructor"""
 207         rational.__init__(self, x, **kwargs)
 208         self.ticklevel = ticklevel
 209         self.labellevel = labellevel
 210         self.label = label
 211         self.labelattrs = labelattrs
 212
 213     def merge(self, other):
 214         """merges two ticks together:
 215           - the lower ticklevel/labellevel wins
 216           - the ticks should be at the same position (otherwise it doesn't make sense)
 217             -> this is NOT checked"""
 218         if self.ticklevel is None or (other.ticklevel is not None and other.ticklevel < self.ticklevel):
 219             self.ticklevel = other.ticklevel
 220         if self.labellevel is None or (other.labellevel is not None and other.labellevel < self.labellevel):
 221             self.labellevel = other.labellevel
 222         if self.label is None:
 223             self.label = other.label
 224
 225
 226 def mergeticklists(list1, list2, keepfirstifequal=0):
 227     """helper function to merge tick lists
 228     - return a merged list of ticks out of list1 and list2
 229     - CAUTION: original lists have to be ordered
 230       (the returned list is also ordered)"""
 231     # TODO: improve along the lines of http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/305269
 232
 233     # do not destroy original lists
 234     list1 = list1[:]
 235     i = 0
 236     j = 0
 237     try:
 238         while 1: # we keep on going until we reach an index error
 239             while list2[j] < list1[i]: # insert tick
 240                list1.insert(i, list2[j])
 241                i += 1
 242                j += 1
 243             if list2[j] == list1[i]: # merge tick
 244                if not keepfirstifequal:
 245                    list1[i].merge(list2[j])
 246                j += 1
 247             i += 1
 248     except IndexError:
 249         if j < len(list2):
 250             list1 += list2[j:]
 251     return list1
 252
 253
 254 def maxlevels(ticks):
 255     "returns a tuple maxticklevel, maxlabellevel from a list of tick instances"
 256     maxticklevel = maxlabellevel = 0
 257     for tick in ticks:
 258         if tick.ticklevel is not None and tick.ticklevel >= maxticklevel:
 259             maxticklevel = tick.ticklevel + 1
 260         if tick.labellevel is not None and tick.labellevel >= maxlabellevel:
 261             maxlabellevel = tick.labellevel + 1
 262     return maxticklevel, maxlabellevel