shadowfacts/fonttools
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[statisticsPen] Another bandaid

Browse Source 
Sigh. I'm probably doing something wrong but I don't understand.
This commit is contained in:
Behdad Esfahbod 2023-11-19 11:09:39 -07:00
parent 0d28975708
commit 21864fc26a
1 changed files with 9 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
Lib/fontTools/pens/statisticsPen.py
View File

@ -64,11 +64,13 @@ class StatisticsPen(MomentsPen):
self.meanY = meanY = self.momentY / area
# Var(X) = E[X^2] - E[X]^2
self.varianceX = varianceX = self.momentXX / area - meanX * meanX
self.varianceY = varianceY = self.momentYY / area - meanY * meanY
# XXX The above formula should never produce a negative value,
# but due to reasons I don't understand, it does. So we take
# the absolute value here.
self.varianceX = varianceX = abs(self.momentXX / area - meanX * meanX)
self.varianceY = varianceY = abs(self.momentYY / area - meanY * meanY)
self.varianceX = varianceX = abs(varianceX)
self.varianceY = varianceY = abs(varianceY)
# Covariance(X,Y) = (E[X.Y] - E[X]E[Y])
self.covariance = covariance = self.momentXY / area - meanX * meanY
@ -96,6 +98,11 @@ class StatisticsPen(MomentsPen):
sum(p.imag * p.imag for p in nodes)
- (sumNodes.imag * sumNodes.imag) / n
) / (n - 1)
# XXX The above formula should never produce a negative value,
# but due to reasons I don't understand, it does. So we take
# the absolute value here.
self.varianceX = varianceX = abs(varianceX)
self.varianceY = varianceY = abs(varianceY)
# Covariance(X,Y) = (sum[X.Y] - sum[X].sum[Y] / n) / (n - 1)
self.covariance = covariance = (