85 lines
2.5 KiB
Python
85 lines
2.5 KiB
Python
from __future__ import print_function, division, absolute_import
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from fontTools.misc.py23 import *
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import math
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from fontTools.pens.momentsPen import MomentsPen
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__all__ = ["StatisticsPen"]
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class StatisticsPen(MomentsPen):
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# Center of mass
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# https://en.wikipedia.org/wiki/Center_of_mass#A_continuous_volume
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@property
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def meanX(self):
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return self.momentX / self.area if self.area else 0
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@property
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def meanY(self):
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return self.momentY / self.area if self.area else 0
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# Var(X) = E[X^2] - E[X]^2
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@property
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def varianceX(self):
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return self.momentXX / self.area - self.meanX**2 if self.area else 0
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@property
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def varianceY(self):
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return self.momentYY / self.area - self.meanY**2 if self.area else 0
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@property
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def stddevX(self):
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variance = self.varianceX
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return math.copysign(abs(variance)**.5, variance)
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@property
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def stddevY(self):
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variance = self.varianceY
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return math.copysign(abs(variance)**.5, variance)
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# Covariance(X,Y) = ( E[X.Y] - E[X]E[Y] )
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@property
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def covariance(self):
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return self.momentXY / self.area - self.meanX*self.meanY if self.area else 0
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# Correlation(X,Y) = Covariance(X,Y) / ( stddev(X) * stddev(Y) )
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# https://en.wikipedia.org/wiki/Pearson_product-moment_correlation_coefficient
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@property
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def correlation(self):
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correlation = self.covariance / (self.stddevX * self.stddevY) if self.area else 0
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return correlation if abs(correlation) > 1e-3 else 0
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@property
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def slant(self):
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slant = self.covariance / self.varianceY if self.area else 0
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return slant if abs(slant) > 1e-3 else 0
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def _test(glyphset, upem, glyphs):
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from fontTools.pens.transformPen import TransformPen
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from fontTools.misc.transform import Scale
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print('upem', upem)
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for glyph_name in glyphs:
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print()
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print("glyph:", glyph_name)
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glyph = glyphset[glyph_name]
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pen = StatisticsPen(glyphset=glyphset)
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transformer = TransformPen(pen, Scale(1./upem))
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glyph.draw(transformer)
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for item in ['area', 'momentX', 'momentY', 'momentXX', 'momentYY', 'momentXY', 'meanX', 'meanY', 'varianceX', 'varianceY', 'stddevX', 'stddevY', 'covariance', 'correlation', 'slant']:
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if item[0] == '_': continue
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print ("%s: %g" % (item, getattr(pen, item)))
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def main(args):
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if not args:
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return
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filename, glyphs = args[0], args[1:]
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if not glyphs:
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glyphs = ['e', 'o', 'I', 'slash', 'E', 'zero', 'eight', 'minus', 'equal']
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from fontTools.ttLib import TTFont
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font = TTFont(filename)
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_test(font.getGlyphSet(), font['head'].unitsPerEm, glyphs)
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if __name__ == '__main__':
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import sys
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main(sys.argv[1:])
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