I got this error also:
/usr/lib/python2.7/dist-packages/numpy/core/_methods.py:55: RuntimeWarning: Mean of empty slice.
warnings.warn("Mean of empty slice.", RuntimeWarning)
Traceback (most recent call last):
File "/usr/local/bin/ocropus-rtrain", line 269, in <module>
network.lnorm.measure(amax(line)-line)
File "/usr/local/lib/python2.7/dist-packages/ocrolib/lineest.py", line 43, in measure
self.mad = mean(deltas[line!=0])
File "/usr/lib/python2.7/dist-packages/numpy/core/fromnumeric.py", line 2716, in mean
out=out, keepdims=keepdims)
File "/usr/lib/python2.7/dist-packages/numpy/core/_methods.py", line 67, in _mean
ret = ret.dtype.type(ret / rcount)
FloatingPointError: invalid value encountered in double_scalars
Please help me